base

Fix minor transition bugs and add capabilities

Some view changes require more flexible transitions than the
defaults provided by Crossfade and TextChange - this change supplies some
of that flexibility.

Also, starting a new transition on a hierarchy undergoing a transition
caused the first to get canceled, then the start values to be retrieved.
The new transition should actually get the start values from the intermediate
state of the views, so we now cancel the previous transition only after the
start values have been captured.

Issue #9756349 Transitions: Crossfade does not handle interruption/reverse correctly
Issue #9295863 Transitions: Add behavior API/flags to various transitions
Issue #9275859 Transitions: Improve mechanism for transition interruption

Change-Id: I5a8c5a12466ddcab9e84e4880930563fa1216f3b