Audio Input and Output

[lnihlen]

On Linux, Scintillator should be able to be both a jack audio source and sink, and those signals should be available to the VGen signal chain. But not for audio synthesis, the audio is pass-through only (modulo lag). The idea being that you could route the output of scsynth to scinsynth, then have scinsynth add a little latency to the audio to synchronize it with the video. Or, if latency is sensitive, route audio both to the audio card and scintillator at the same time, and the video will just lag a bit.

[lnihlen]

PRs #125, #126, #127 add realtime audio ingestion into video texture via PortAudio.