perform send of audio buffer on main thread
Merge remote-tracking branch 'upstream/master' into mixer-crash
resolve conflicts on merge with upstream master
make the audio mixer socket non-blocking so it doesn't halt waiting for data
underscore the sample length variables in AudioRingBuffer
some refactoring for member variables in AudioRingBuffer
fixes per code review comments
Merge pull request #261 from birarda/mixer-crash

de-thread the audio mixer to hopefully resolve its constant restarts