Add MIDI GUI tab and learn function

[ignotus666]

Adds a MIDI tab to the Settings menu and exposes the MIDI parameters so they can be changed via the GUI. MIDI CC numbers can be automatically set using "learn" buttons that when pressed, listen for an incoming MIDI message and store it. Starting Jamulus with --ctrlmidich command line arguments overrides and replaces those set via the GUI.

The MIDI-in port can be enabled/disabled at runtime instead of it being determined at launch by the --ctrlmidich parameter or by making it permanently open. This means that user names are prepended by a number depending on whether the MIDI in port has been enabled or not (as is the case now).

I've also ditched the "Offset" term, at least for the GUI. It's a hangover from the days when that's what it was, a value hard-coded for a specific Behringer device, but in the current context it no longer makes sense.

CHANGELOG: Client: Added MIDI tab to Settings GUI exposing MIDI parameters. MIDI Learn feature also added.

Context: Fixes an issue?

Does this change need documentation? What needs to be documented and how?

Needs to be documented.

Status of this Pull Request

Working on Linux, Windows and macOS but should be tested more thoroughly.

What is missing until this pull request can be merged?

Further testing and code review.

Checklist

• I've verified that this Pull Request follows the general code principles
• I tested my code and it does what I want
• My code follows the style guide
• I waited some time after this Pull Request was opened and all GitHub checks completed without errors.
• I've filled all the content above

[softins]

Thanks for this contribution. It looks like a useful feature.

I will be happy to test it in due course, on Linux, Windows and Mac, but at the moment most of my kit is packed away for a pending house move.

[ignotus666]

@softins thanks - no worries, I guess there will be plenty of time for testing before this ever makes it in (if it does).

Hope the house move goes smoothly.

[ann0see]

Nice!

I'd like to open a discussion:

1. Do you think a separate MIDI tab is useful or does it add clutter?
2. Is there a better word instead of "Learn" for the detector? How can we make the feature clear to the user? Would a dynamic text field showing currently pressed buttons be better? (I'm unsure as this could be more complicated)

[ignotus666]

@ann0see

1. Given the number of MIDI settings, I don't see how it would fit in somewhere else without cluttering up that section in a worse way. I think it merits its own tab.
2. "Learn" is a standard term for this feature. I see and use it in many other MIDI applications. Maybe "MIDI learn"? But I think that might make the button too large.

In any event, this is still under development as I'm finding that some of my implementations are far from perfect. E.g. the way the MIDI in port is currently kept open I think has been done wrong, so I'm working on that. I'm testing a version where the MIDI port can be enabled/disabled at runtime, as among other things it affects whether numbers are prepended to user names in the mixer board - if you're not using MIDI you won't want that.

The main purpose for opening this PR was to generate builds for other platforms for testing, but for now it's just a PoC that's far from finished, so any suggestions are welcome.

[ignotus666]

Tested on Linux, Windows (no JACK) and macOS (legacy and non-legacy), and it seems to be working on these three platforms at least.