moved styles support to Plot.prepare
allow saving charts to files (and convert all charts tests to create files instead)
* started to document charts
* use .. note:: where applicable (there are probably more place where it should be used)
allow charts to be saved to several formats at once by using '&' in the extension: eg: fname='plot03.png&pdf'
trying wh show() instead of show(block=True)
more work on documenting the charts functions
more TODO
document ViTables integration
made grid = True by default for plot()
* removed stacked 3d bar charts
   they are too buggy and unlikely to work any time soon (see https://github.com/matplotlib/matplotlib/issues/155/ and https://github.com/matplotlib/matplotlib/issues/1292/)
 * further cleanup/simplify charting code (in part thanks to the removal of stacked bar3d)
kill commented code and add docstring
more work on the charts documentation
more work on the charts documentation
kill bar3d entirely, it's too buggy
kill bar3d from the doc
move ndim() to utils
updated changelog for the prerelease
updated versions for the prerelease
added images for the graphs in the charts doc
add stuff to .gitignore