personal fixes for midi export

[linux-leo]

I made some changes until midi export worked the way I expected it to. These changes are probably a bit opinionated, but I figured they might still be useful to you for implementing export options. That's why I opened this as a draft PR. It also includes a fix for sending Note-Off Commands

[juzzlin]

Thanks! I have been working on this in the big way so that PC and Bank can be optionally enabled in the export dialog. Also, Noteahead will try to match the port names on MIDI import and set programs and banks accordingly. And of course changed unit tests to match this.

[juzzlin]

Does this work now in master like intended? :)

[linux-leo]

Almost! An Issue I still have is that percussion instruments aren't played on midi channel 10. IIRC the code skips over that channel when assigning tracks to channels. That's technically correct for melodic instruments but it doesn't allow me to have any percussion instruments on that channel. I see three options to solve this:

1. play tracks on channel 10 if they're set as a drum track
2. Auto assign tracks to channels except when the track specifies to be played on channel 10
3. Don't auto assign tracks and play them on the same channels in the midi export as during live playback. (the channels specified in the tracks themselves)

Personally I prefer option 3 since it guarantees the midi export plays exactly how I hear it during live playback, but any of the three solutions would help.

[juzzlin]

Thanks for your input! Could you create an Issue about this? :)