MouseTracker Touch Fixes - Flick Defaults and Bubbling

Flick gesture settings defaults set to better values.
Removed touch event model bubble cancelling so viewer controls show on
touch contact.
Stiffened the spring
iOS touch enter/exit fix
iOS touch enter/exit fix for BUttonGroup
Merge pull request #387 from msalsbery/Touch-Enter-Event

MouseTracker Touch Fixes - Flick Defaults and Bubbling