REL: v3.2.2

This is the second bugfix release of the 3.2.x series.

This release contains several critical bug-fixes:

 - support fractional HiDPI scaling with Qt backends
 - support new Python and fix syntax errors in legacy Python
 - support new Qt 5 and fix support for Qt 4
 - fix animation writer fallback
 - fix figure resizing
 - fix handling of large arcs
 - fix issues with tight layout
 - fix saving figures after closing windows or under certain size
   conditions
 - fix scatter when specifying a single color
 - fix several memory leaks
 - fix unexpected autoscaling behavior
 - fix various issues with usetex
 - various minor bug and documentation fixes