Blender Git Loki

Initial support of audio scrubbing in blenderplayer.

Still lots of corner cases to check:

* sound FPS not changing with speed settings of player
* picture and video still not 100% in synch
* Haven't checked what happens when audio is finished.

Some changes were made to make things nicer:

* Scrub now initiates on mouse click instead of mouse motion, makes
things more predictable.
* When scrubbing a movie with sound, don't pause playing after
scrubbing.