HISTORY:
post 1.12:
 usability: Added support for search paths to find data files (table/search path)
 fixed bug: incompatiblity between fillbetween and babel
 fixed bug: 'compat=1.9' (or newer) failed to work with log bar plots
 fixed bug: javascript incompatibility between Acrobat reader DC and clickable lib
 fixed bug in polar axes: repaired default axis label positions
 fixed bug in polar axes: repaired support for sloped descriptions
 utility function \pgfplotsforeachungrouped: added support for \breakforeach
 new feature: 'xtick distance' allows to define tick positions by distance
1.12.1: minor bugfix release
 fixed bug: incompatibility of 1.12 with unicodemath
 fixed bug: lua backend failed to work with table input and dependency on \coordindex
 fixed bug: lua backend failed with 'forget plot'
1.12: scalability + performance
 scalability: reduced TeX memory consumption for huge inline tables
 scalability: lualatex allows bigger 3d graphics
 scalability: lualatex now reduces compilation time for huge 3d graphics
(requires \pgfplotsset{compat=newest} at the time of this writing)
surf shader=faceted: time reduced to 61% of pdflatex
(\addplot3[surf,samples=70] {exp(x^2y^2 +x*y)})
surf shader=interp: time reduced to 25% of pdflatex
(\addplot3[surf,shader=interp,samples=70] {exp(x^2y^2 +x*y)})
surf shader=interp, parametric: time reduced to 36% of pdflatex
(\addplot3[surf,shader=interp,z buffer=sort, samples=50,domain=1:0,y domain=0:2*pi] ({sqrt(1x^2) * cos(deg(y))}, {sqrt( 1x^2 ) * sin(deg(y))}, x);)
surf shader=faceted, parametric: time reduced to 40% of pdflatex
(\addplot3[surf,z buffer=sort, samples=50,domain=1:0,y domain=0:2*pi] ({sqrt(1x^2) * cos(deg(y))}, {sqrt( 1x^2 ) * sin(deg(y))}, x);)
 scalability: lualated now reduces compilation time for boxplots.
10000 input points from table: time reduced to 23% of pdflatex
 fixed bug: 3d axes where all axes used log scale produced compile failure
 fixed bug: axis equal did not respect "disabledatascaling"
 fixed bug: mesh legend was confused by color input=explicit
 fixed bug: colorbar style did not reset zmin/zmax
 fixed bug: memory allocation in FPU consumed too much memory
 fixed bug: boxplots: removed compilation error due to spurious spaces in options list
 fixed bug: boxplots: now uses standard quantile estimators: has all 9 estimators of R and uses the same as in Excel as default (as of compat=1.12)
 fixed bug: boxplots: sometimes failed to compute boxplot statistics for special inputs
 fixed bug: boxplots: now, it sets 'mark=*' for outliers if there is no mark (compat=1.12)
 fixed regression: compat=1.11 broke arcs inside of axis
 new feature: ensured that arcs inside of axis make use of 'axis cs' and 'axis direction cs' automatically
 new feature: ensured that (0:1) is evaluated with axis cs
 fixed bug: precision of transformation cartesian to polar was too low (added atan2 to fpu)
 fixed bug: z buffer caused 'mesh legend' to produce a compile error
 new feature: added 'y filter/.expression={y==3 ? nan : y}' to simplify coordinate filters
1.11: usability + bug fixes.
 new feature: "hide obscured x ticks=false" to disable the feature which hides ticks
 simplified UI for symbolic coords: now, it accepts unexpandable
dictionary entries including umlauts, undefined macros, math mode, ...
 simplified UI for symbolic coords: added magic prefix
[normalized] to allow something like xmin={[normalized]0.7}
 simplified UI for custom annotations: one does not need to say "axis cs" any longer;
coordinates like (1,2) are now automatically interpreted as (axis cs:1,2)
 new feature: 'type ticklabels with struts' improves baseline alignment of tick labels
 new feature: 'trig format plots=rad' allows to use radians in trigonometric evaluations
 simplified 'external lib': added driver autodetection for pdflatex, lualatex, xelatex, dvips
(\usepgfplotslibrary{external}, or, with the next PGF release, \usetikzlibrary{external})
 simplified UI for \addplot coordinates: now, it expands macros as it goes.
 new feature: 'intersection segments' now accepts negative indices to count from the last backwards
 simplified UI: 'intersection segments' now accepts new syntax with 1based indices (old 0based are still supported)
 fixed bug: fillbetween has had a problem with pins on input paths
 fixed bug: now, 'stacked ignores zero' is no longer applied to error bars.
 fixed bug: tick lines were drawn incorrectly for centered axis lines in 3d
 fixed bug: variable=u failed to work in some contexts
 fixed bug: fill between implicitly activated layers, but did not install the
correct layers for grid lines etc.
 fixed bug: z grid style was applied to y grid style
 fixed bug: using 'x=1cm' failed to work in axis descriptions (legends)
 fixed bug: mesh legend failed to work with 'shader=interp'
 fixed bug: bounding box of shader=interp was wrong if there were transformations.
 fixed bug: added support for \addplot graphics in ConTeXt
 fixed bug: external lib failed to work with dvips (since PGF 3.0.0 I suppose); now it produces correct bounding boxes
 fixed bug: \pgfplotstablenew can now overwrite existing tables.
 fixed bug: extra ticks near intersections of axis lines were hidden
 fixed bug: 'intersection segments' did not work with 'cycle'
 fixed bug: 'intersection segments' did not update the last tikz point
 fixed bug: tick lines/grid lines have been clipped when they were near the boundary
 fixed bug: soft clip decoration failed to apply the transformation matrix
 fixed bug: polar axes and units library resulted in broken bounding box
 fixed bug: \addplot[stack plots=false] used to work up to 1.8, but failed until now. Fixed.
 fixed bug: hist/density was broken since some time
1.10:
 new feature: fill between plots (library fillbetween)
 new feature: concatenate intersection segments (library fillbetween)
 fixed bug: xelatex failed to run contour external
 fixed incompatibility with \label and \usepackage{mcaption}
 fixed bug: histograms produced wrong point meta
 fixed bug: histograms reported the wrong 'plot name' and confused shifts of bar plots
1.9:
 new feature: asymmetric error bars
 new feature: activated math parser for axis limit arguments, arguments in axis cs, and domain argument in log plots
 new feature: stacked bar plots place their 'nodes near coords' correctly in the middle and print the increment (compat=1.9)
 new feature: stacked bar plots suppress empty increments (compat=1.9).
 new feature: 'scatter/position=relativeabsolute' allow to position 'nodes near coords' absolutely.
usecase: bar plots + nodes near coords which are at, say, y=0 rather than their y value
 new feature: integration of smooth shadings & autoCMYK conversion
\usepackage[cmyk]{xcolor} or \selectcolormodel{cmyk} will reconfigure pgfplots to use CMYK (documentwide)
 new feature (advanced audience only): programmatic access to data coordinates during the visualization phase
> allows much more customization for error bars, stacked plots, nodes near coords.
 wrote beginner tutorials
 fixed bug: error bars and point meta did not work together
 fixed bug: stacked plots did not respect 'visualization depends on'
 fixed bug: luatex 0.76 is not backwards compatible; added version switch
 fixed bug: ternary library precision has been improved
 fixed bug: problem with axis limits very close to 0
 fixed bug: colormap specification limit case produced out of bounds exception
1.8:
 new feature: tight bounding box even if the axis is no box and bb excludes clip path
 new feature: mesh/color input=explicit
 new feature: shader=interp now has drivers for both dvipdfmx and xetex
 new feature: support for more color spaces in colormap definitions
 new feature: shader=interp and devicelevel gray colorspaces
 new feature: 'contour/contour dir=[xyz]' to draw contours in different directions
 new feature: statistics library with boxplot handler (both boxplot prepared and automatic computation)
 fixed bug: 3d centered axis lines and label placement (requires compat=1.8 or higher)
 fixed bug: axis lines and placement of labels, tick scale labels, and reversed axes
(requires compat=1.8 or higher)
 fixed bug: filtering out coords from a mesh plot failed
 fixed bug: every legend image post was not respected inside of \ref{plotlabel}
 fixed bug: highorder patches computed the shader=flat mean in a wrong way.
 fixed bug: remember picture inside of pgfplots axes failed (due to cell picture)
 fixed bug: now, the tick scale label will be omitted if there are no ticks
 fixed bug: axis box path was not closed
 fixed bug: the bounding box was nonempty even if the axis was hidden.
 fixed bug: autoalignment of nodes near coords failed for xbar plots
 fixed bug: providing bar width / bar shift in terms of axis units did
not work with [xy]bar and nodes near coords
 fixed bug: transformation 'data cs=cart' > polar is more robust now
 fixed bug: code did not compile against pgf 2.00
 fixed bug: patch plot lib and shader=interp,patch type=biquadratic
 fixed bug: context path searching issue (pgfplots.lua)
 fixed bug: shader=interp and dvips driver
 fixed bug: error bars with explicit relative input failed
1.7
 added feature: 'bar shift' and 'bar width' can now be expressed in terms of axis units (compat=1.7 or higher)
 fixed incompatibility regression pgfplots 1.6.1 pgf 2.10: layers
 fixed incompatibility pgfplots and imakeidx
 added feature: 'enlargelimits={abs=1cm}', i.e. enlarge by dimension rather than unit
 patchplots lib: added patch type=bicubic
 patchplots lib: added support for global paths (fillable)
 patchplots lib: added patch type sampling feature
 patchplots lib: improved usability (documentation and improvements)
 fixed path issues in context: moved lua input file to tex/generic
 fixed bug: \ref{legendimage} inside of legend text was wrong.
1.6.1:
 fixed incompatibility lualatex,shader=interp, and german package (introduced in 1.6)
1.6:
 added support for layered graphics (main use case: multiple axes and layers)
 added support for second colormap in mesh plots (mesh/interior colormap name)
 added support for scopes inside of axes
 contour plots: added ability to provide list of discrete labels (mesh/levels)
 empty lines are interpreted as interruptions in data plots (was undocumented since 1.4)
 added more scaling options to 'scale mode=scale uniformly' (affects axis equal in 3d
and \addplot3 graphics)
 fixed wrong implementation of 'axis equal' and 'unit vector ratio' in 3d
(backwards compatible for 2d, but not for 3d  the 3d implementation was plain wrong)
 fixed incompatibility of lualatex and shader=interp
 fixed bugs/added features around \addplot3 graphics
 fixed bug: colorbar did not support ymode=log
 fixed a couple of minor bugs
 fixed bounding box computation for clip=false,axis lines=none
1.5.1:
 more operations for FPU library (==, !=,<=,>=,?)
 fixed bug in usage of decorations in \addplot
 bugfix for contour prepared format=matlab
 added 'const plot mark mid' and 'jump mark mid' plot handlers
 nodes on a plot (\addplot ... node[pos=] {};)
 'trim axis group left' and 'trim axis group right'
 bugfixes for polar axes and log+stacked plots
 added style 'log ticks with fixed point'
 introduced patched tikz paths to simplify circles and ellipses within an axis
 patchplots lib: patch type=polygon
 some more bugfixes
1.5:
 Contour plots,
 Histograms,
 Quiver plots,
 patch plots (library)
 Triangle Meshes
 Bilinear Elements
 Quadratic Triangles
 Biquadratic Quadrilaterals
 Coons Patches
 Discrete colorbars,
 Table sorting,
 Linear regression,
 Ternary diagrams,
 Tieline Plots
 Smith Charts
 Polar axes,
 Empty lines in input files result in interrupted plots,
 PDF user defined coordinate mouse popups
 CMYK colormaps and shadings,
 new markers and cycle lists
 access to axis limits,
 \addplot3 graphics: pgfplots draws an appropriate axis for a threedimensional(!) external png graphics
 3D axes: support to provide explicit unit vectors:
 explicit unit vectors
 explicit unit vectors which are uniformly rescaled to match width/height
 3D axes: improved support for unit vector ratios
 improvements of the groupplot styles
 preliminary support for (2d) bar plots in 3d axes
 new shader 'faceted interp'
 table package:
 'every nth row' style
 'comment chars' key to define comment characters in input files
 'skip first n' style
 lots of smaller bugfixes (see ChangeLog for details)
1.4.1:
 improved compatibility to gnuplot 4.4
1.4:
Version 1.4 contains several new features, mostly work on details.
It fixes many bugs and provides the following improvements:
 detached legends
 detached colorbars
 ybar (and similar plots) can now be mixed with other plot types
like line plots.
 improved legend formatting
 added 'restrict x to domain*' which cups coordinates outside of a specified domain (same for y and z)
 Added support for linear regression
 Inline tables,
 Lots of bug fixes
The next version will make a greater step when it is stable.
1.3.1:
Version 1.3.1 is a bugfix release containing
 improved parametric plots with gnuplot
 improved normalsize, small and footnotesize scale styles and added tiny
 a lot of bugfixes
1.3:
 improvements for two dimensional visualization, among them
 axis equal,
 color bars,
 nodes near coords,
 jumps in plots,
 improved description positioning,
 reverseable axis directions,
 simpler alignment of adjacent axes,
 units and a simplified user interface,
 new three dimensional line, scatter, mesh and surface plots,
 a copy of the automatic pdf externalization library,
 an improved manual enhanced with a lot of pdf cross references.
1.2.2:
 fixed a problem with the samples key,
 provides some smaller fixes and some manual improvements.
 added plot graphics.
1.2:
 completely rewritten math expression parser with extended data range,
 colormaps for scatter plots
 fine tuning for plot parameters.
 table package has been extended and is now a fully featured table typesetting, computing and postprocessing tool.
