Add support for segment sets (groups of segments)

[blazoncek]

Up to 4 segment groups can be defined.
Visible only when more than 2 segments are created and has no other functionality other than allowing quick segment selection in UI.

NOTE: Reduces possible audio simulations from 8 to 2 (keeping BeatSin and WeWillRockYou) to accommodate segment groups without increasing Segment RAM footprint.

[blazoncek]

@Aircoookie would you agree with adding segment groups?

[Aircoookie]

This feature sound interesting, will finally check it out soon!
Two points in advance:

• Maybe we should name this feature segment set/bunch/cluster/collection so it won't be confused with the Grouping grp property
• Not a fan of cutting sound simulation modes, was rather hoping to add more in the future. Keeping the existing RAM footprint is good too though. I would keep the extra simulation modes commented out for now and we can consider expanding the segment options flag union to 32 bit in the future.

[blazoncek]

As sound (if used from microphone) affects all segments equally I would rather see a global sound simulation option instead of per-segment one.

With such approach the implementation with 1 bit could mean 0 use simple beatsin (per segment) and 1 use global.

And honestly stuffing more simulation options could be done in usermod.

[blazoncek]

I agree on name change so instead of segment groups we can use segment sets.

[blazoncek]

@Aircoookie any chance to give this another try?
I have plenty of bugfixes queued. Waiting for this PR to be merged or rejected.

[Aircoookie]

Ready to be merged! (finally, sorry it took so long)
Ideally the g-icon would also show in expanded segment view (though the only place I see that would be available is above the delete button), though this does not have to be added immediately.