uix:TextInput fix introduce `use_handles`, fix usage issues with
selection handles. closes #1628
uix:TextInput fix handles persistance on special keys
uix:TextInput Minor fixes for selection handles
uix:TextInput use a better selection handle for cursor
uix:TextInput fix for dissapearing handles on android
uix:TextInput improve handle positioning, update text when selection is
adjusted using selection handles
Merge pull request #1647 from kivy/selection_handles

Usage changes, fixes for selection handles.