Bug-fix release for the 1.4 series.

 - reverts the changes to interactive plotting so `ion` will work as
   before in all cases
 - fixed boxplot regressions
 - fixes for finding freetype and libpng
 - sundry unicode fixes (looking up user folders, importing
   seaborn/pandas/networkx with macosx backend)
 - nbagg works with python 3 + new font awsome
 - fixed saving dialogue in QT5