Better midi parser, handles running status. Also support for all notes off

[bwhitman]

• starting in on midi parser (and also side work on mpremote for it)
• fixed midi parser, and allowing midi.py to do all notes off

[bwhitman]

I still can’t test running status but I’ve run through it in my head and it should work. All notes off (tested via Ableton) does work, and we now parse every midi message in the midi 1.0 specification properly (midi.py only handles a few, but it shouldn’t break other stuff)

I tested USB midi on Tulip CC, still is fine

I tested IAC midi on Tulip Desktop mac, still is fine

[bwhitman]

#344