Change the assumed button width for the kerning class selector window size computation.
Fix a few things about which Coverity complained.
Merge pull request #2001 from fontforge/coverity_20141216_1

Fix a few things about which Coverity complained.
Add UI for adding new classes
Add sorting of anchor class coverage tables
Add open flags to read all ttf tables
Fix ordering of mark glyphs in coverage tables
Merge pull request #1999 from fontforge/fix_kerning_class_selection_window_width_1

Fix the kerning class selection window size.