interaction support for generic midi devices

[hv10]

I would love to have a way to map a connected midi device manually, either by mapping each pad/ key/ button/ slider manually (like in Ableton) or by mapping ranges of keys (useful for live performances with a keyboard)

[mmckegg]

Hey @hv10,

Work has been started on this over here: #215

Unfortunately I need to do a bunch of refactoring before I can merge these changes in. But it will make things much more friendly to other controllers 😄

I'm very keen for this to be a thing!