Add ANativeWindow API for directly drawing to the surface bits.

Also other cleanup and fixes:

- We now properly set the default window format to 565.
- New APIs to set the window format and flags from native code.
- Tweaked glue for simpler handling of the "destroy" message.
- Um, other stuff.

Change-Id: Id7790a21a2fa9a19b91854d225324a7c1e7c6ade