Fix spinning cursor on OS X

[slimsag]

• Fix the spinning cursor / UI deadlock on OS X.
• Make less memory allocations when updating the texture / video display.
• A better OpenAL usage (no flushing, better buffering on channels, and a re syncing pattern).

This does not stop the clicking issue entirely.

[slimsag]

I am going to bed now -- but I will send another PR sometime tomorrow (if you are ok with the above changes) from my apudebug branch.

I researched further into the cause of clicking, and to completely rule out Azul3D I did so against the sdl backend. I found that, at least on my system, the APU only sends on average 34khz audio over the audio.Input() channel.

Obviously, you can't playback 34khz audio at a rate of 44.1khz 😞. I think it's likely to be a bug in your code somewhere, but I don't know enough about NES emulation to know for sure.

Details at: slimsag@be7afa1

P.S. The timestamps on my commits are way off, something's up with my system clock =)