MIDI for light: add settings ui

[ekordas]

Adds Setting definition for UI of the Midi for Light Script

[ronso0]

Thank you for this PR.
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Do you mind attaching a screenshot of the new settings?

[ekordas]

I allready signed the agreement.

Here is a screenshot:

[ronso0]

Okay, thank you, I didn't remember you already worked on MIDI for lights.

The VU checkboxes could use more human-readable labels, not just the internal variable names, no?

I didn't work with the controller settings, yet, wasn't there an option/flag that would arange group items horizontally if the preference page allows it?

[ekordas]

I didnt work with the controller settings either, If there is a documentation for it i can set other flags. Leaving the Orientation to unset flipps checkboxes to a row while resizing the settings wich is really destroying the layout:

So i leave it to vertical.
The Labels are changed in the next commit.

[JoergAtGithub]

If there is a documentation for it i can set other flags.

@acolombier Do we have this described in the manual?

The best reference is the mapping for the S4 Mk3: #12995

[ekordas]

The Mapping xml file is described at https://github.com/mixxxdj/mixxx/wiki/MIDI%20controller%20mapping%20file%20format but not the ui Stuff. I Used the mentioned diff as reference.

[ekordas]

The<row orientation="vertical">seems to do the intended behavior, but if the vertical list of checkboxes is flipped to a row it does not flip back. And it does not matter how slim you resize the window.
The section above does change to a row if the Size allows it and back, but it seems there is a Problem with a long list of checkboxes.
Since the script is more aimed at developers and technical applications I personally would not bother making it pretty to much. It only requires a little scrolling.
Following is a new attempt: