Allen & Heath Xone K2 updates for 2.3

[Be-ing]

1. Add a new layer for the bottom buttons for the new intro & outro cues. From top to bottom, they are mapped:

intro start
intro end
outro start
outro end

The buttons in this mode are amber when a cue is set. Pressing a button with shift unsets the cue, just like hotcues.

2. Remap the top encoder. In my experience, I have needed to adjust gain more often than use the jog function, so I swapped those. The encoder now works like this:

turn: gain adjust
turn + shift: jog
turn + supershift: key adjust

press: reset gain
press + shift: master sync
press + supershift: reset key

Feedback would be appreciated. @ferranpujolcamins, @ywwg

[Be-ing]

I have been using this since #1242 was merged in April and it has been working well for me.

[foss-]

tested works great

[Be-ing]

I added a new feature. On the intro/outro cue and hotcue layers, the buttons can now be used for seeking with shift. The top two buttons seek quickly forward/back and the bottom two seek slowly. Deleting cues can still be done with supershift (holding bottom right and bottom left buttons). This allows for setting cues precisely. Before I had to switch to the loop layer for beatjumping (which does not allow fine seeking easily), then switch back to a cue layer, or alternately reach for the scrolling waveform to seek. Now I can do it all from one button layer on my controller.

At first I tried using the documented fwd/back Controls but found they went too fast. I was considering adding a new Control to the engine for slower seeking but found that fwd/back are just wrappers around the undocumented rateSearch Control. I documented rateSearch on the wiki.

[Be-ing]

tested works great

Thanks. I'd like to play at least one live set with the latest updates before merging.

[uklotzde]

@Be-ing Please merge it whenever you think this is ready! Only a limited set of users is able to test the mappings, so a review by us outsider is purely optional.

[Be-ing]

I think this is ready but I want to test it more before merging. I may end up adjusting the seeking rates.

[Be-ing]

I swapped loop size adjustment & beatjump/loop move, so now loop halve/double is the default action of the bottom two buttons in loop mode and beatjump/loop move is the shift action. I previously used beatjump/loop move frequently for seeking, but now that the intro/outro cue and hotcue buttons can seek with shift, I don't need quick access to beatjumping.

[Be-ing]

I played a 2 hour set with this last night and l am happy with the changes. I rearranged the bottom button layers so the intro/outro layer is the default when Mixxx opens. I spend most of my time on this layer, especially now that I don't need to switch to the loop layer for seeking. Implementing a way to seek on the cue layers was exactly what this mapping needed. :)

I documented the changes on the wiki.