Finish implementation of multiple pointer support for MotionEvent.

The major things going on here:

- The MotionEvent API is now extended to included "pointer ID" information, for
  applications to keep track of individual fingers as they move up and down.
  PointerLocation has been updated to take advantage of this.

- The input system now has logic to generate MotionEvents with the new ID
  information, synthesizing an identifier as new points are down and trying to
  keep pointer ids consistent across events by looking at the distance between
  the last and next set of pointers.

- We now support the new multitouch driver protocol, and will use that instead
  of the old one if it is available.  We do NOT use any finger id information
  coming from the driver, but always synthesize pointer ids in user space.
  (This is simply because we don't yet have a driver reporting this information
  from which to base an implementation on.)

- Increase maximum number of fingers to 10.  This code has only been used
  with a driver that reports up to 2, so no idea how more will actually work.

- Oh and the input system can now detect and report physical DPAD devices.
2 files changed