More note_repeat properties for scripts

[yannxou]

I'm developing this MIDI script in Python to use the Yamaha Reface CP as a Live control surface:
https://github.com/yannxou/RefaceCPLiveControl

I was looking now to add some note repeating there too. It seems that the note_repeat type only has a repeat_rate property but I thought it'd be great to add more settings into it like:

* Number of repetitions per note: Some property like this would allow to use the note_repeat as a realtime quantizer when set to 1 repetition per note.

* Note velocity: A way to change the repeated note velocities from the script would be awesome for devices that do not support aftertouch.

* Note length: A way to change the length of the repeated notes from the script would be very useful, specially when used in synths rather than drums or percussive sounds.

As a final thought, maybe it'd be better instead (or both) if there was some arpeggiator object that could be configured from the script. This would open lots of possibilities for many controllers.