Remove polyvoice from juno6

[bwhitman]

the juno6 UI should use music_map to set patches, and then do its thing for parameter changes / CCs. right now it boots extra voices and kills polyphony while it's running

[bwhitman]

We have removed polyvoice (in branch juno6-amy) and now use AMY's built in voices to send multiple messages to multiple voices. (Our "we have polyvoice-at-home", midi.py, is handling voice stealing but currently is not handling release order in the same way polyvoice did. We can fix that.)

This means juno6 starts up with Tulip handling note ons/offs/pitchbend/PC the same way as if it was never run, but will send its own patch setup messages to AMY at start and at any parameter change. juno6 also responds to MIDI CCs using a 2nd MIDI callback while it is running (even if not active on the screen.)

The next step for all this is to have a system level UI for patches, outside of juno6, so that users can set patches per channel in an interface and then use things like juno6 to modify patches when needed. To do this, we'll remove the patch selector from juno6 and let users assign patches from a future voices app. juno6 can edit any Juno-style patch active in the voices app with the channel selector.

Later, we'll want Tulip to be able to save modified patches from any voice or synth type to the custom set of patches (1024-1055) and to disk for reloading.

Will merge after more testing and getting a first version of voices out.

[bwhitman]

(Oh, arpegg.py is disabled right now, but that's a quick fix to get back. Will fix that before merging.)

[bwhitman]

Arpegg works, juno6 no long uses polyvoice but instead our system midi.py (which is polyvoice under a new name)

Some issues with the juno6 UI (channel selector) and the voices UI (piano, and arpegg status isn't updated) but we're almost there.

[bwhitman]

Merged! Will log the remaining issues.