Start moving Clock to code

Move Clock into code; make a PhaseController

JerkyTreats

This is mainly on cleanup and extras. I want to move BP_MainClock into code, as a PhaseController for activating the Clock, then update Drum/Instrument to be PhaseControlled as well.

I do need to think a little bit about never-ending phases. It might be that Clock/Drum are not PhaseControllers themselves, but are driven by a separate PhaseControlled entities.

I also merged the PR after this, as it was getting long in the tooth.