sevonj

**@dsgallups - #39** I think this would be better done in smaller increments and with extensive automated unit tests and manual listening tests built beforehand. There's a lot of potential...

If you use Rodio for audio, check out my implementation for reference: ~~https://github.com/sevonj/sfontplayer/blob/master/src/audio/midisource.rs~~ Edit: the file has moved. Here's a permalink: https://github.com/sevonj/sfontplayer/blob/8049ec5c73ff8b53834062e496431d5a0af2594b/src/player/audio/midisource.rs