Groove shuffle implementation

[eethann]

This is a first implementation of groove in Orca. It doesn't handle restarts gracefully (wherever you restart will become a downbeat relative to the groove), and the clock needs to be restarted when groove is changed. Basic functionality seems to work though: groove:X;Y;Z sets ratios between ticks, groove:X gives the standard MPC style shuffle, groove:50 is the default, linear clock.

[neauoire]

If you wanna complete the implementation of the groove command I'll merge it :)

[eethann]

Updated to use a setTimeout loop in the worker process and refactored BPM and groove to update the state of that clock without needing to restart when BPM or groove is changed.

Didn't test with animated clocks yet. Used globals for worker process state.

[eethann]

I think this should be good to merge at this point.

[eethann]

One possible enhancement would be jitter correction on the clock: check actual time against scheduled time each tick and compensate. Not essential though.

[dfischer]

What ever happened with this? Any bugs?