Implement sound playback (still lots of bugs)
Implement sound playback (still lots of bugs)

* Getting a lot of underflow (i.e. clicks + pops)
* Square waves sometimes seem to be playing too long
* Channel 3 (wave) sounds a bit "harsh" sometimes?
* Channel 4 (noise) still isn't implemented

But a lot of stuff works and sounds pretty good.

binji/binjgb,binji/binjgb,binji/binjgb