1. Single finger tap performs a click.
2. Single finger movement moves the pointer (hovers).
3. Button press plus movement performs click or drag.
While dragging, the pointer follows the finger that is moving
fastest. This is important if there are additional fingers
down on the touch pad for the purpose of applying force
to an integrated button underneath.
4. Two fingers near each other moving in the same direction
are coalesced as a swipe gesture under the pointer.
5. Two or more fingers moving in arbitrary directions are
transformed into touches in the vicinity of the pointer.
This makes scale/zoom and rotate gestures possible.
Added a native VelocityTracker implementation to enable intelligent
switching of the active pointer during drags.
Change-Id: I7b7ddacc724fb1306e1590dbaebb740d3130d7cd
247da72a5b