Added EuclideanCC "Continuous Controller" change events

[dronus]

A first attempt on MIDI Continuous Controllers, in respect of #11 :

• an additional generator, cloned from EPG, that generates CC events for settable CC controller with settable constant value. May need individual graphical layout, to differentiate from EPG.
• two additional modes for Euclid FX, that modify either the CC number or CC value
• output made cabable of sending 'CC' events
• basic documentation at README.md (no further pics)
• tested with Dexed so far

Maybe we should remedy code duplication for further proccessors by putting utils like pattern generation and dial graphics ("necklace") to a central location?

[dronus]

Question is, if this is a understandable architecture. Pro: -easy to implement -UI /algorithms already known from the EPG. Cons: -CCs are meant to be continous (both in time and value)

So optimally we would send a CC control change event everytime it is neccessary and useful. Eg. implement continuous ramps / curves for the EuclidFX, and let the EuclidFX emit CC events as needed, even without incoming events. Much more complicated of course. But would remove the need for the just introduced "Euclid CC Generator" again, which would be cool.

[dronus]

Dropped in favor of newer implementation.