REL: v3.3.2

This is the second bugfix release of the 3.3.x series.

This release contains several critical bug-fixes:

* fix Axis scale on twinned Axes
* fix auto-close of Figures in nbagg
* fix automatic title placement if Axes is off the Figure
* fix autoranging of log scales with barstacked histogram
* fix extra redraws when using Button or TextBox widgets
* fix imshow with LogNorm and large vmin/vmax ranges
* fix plotting Pandas DataFrame with string MultiIndex
* fix scatter with `marker=''`
* fix scatter3d color/linewidth re-projection
* fix state of mode buttons in TkAgg backends
* include license files in built distribution
* reduce Visual C++ runtime requirements on Windows