Add a sprite controller.

Refactored PointerController to extract the surface management
code to a new component called a SpriteController so that it can
be used to move finger tracking spots around the screen as well.
The SpriteController is designed to fully decouple the client from
any latency introduced by surface transactions and drawing.
All sprite updates are performed asynchronously on the Looper using
a copy of the sprite state.

Added a stub SpotController implementation for touch pad UX.
It will be implemented in a subsequent patch.

Fixed a little bug in pointer orientation changes when entering
DISPLAY_ORIENTATION_90 the x offset was clobbered.

Change-Id: Ib25d162d577c9b354cb74d5d761c3c9f9f438d42