More linear groups

Linear grouping is where the magic happens imo, because it stops patterns getting too messy, but it would be much more useful if we could have more than one group. One for the kick and bass, one for hats, one for percussion etc etc etc

I don’t think I need to go into detail explaining why

Hopefully someone will see this and implement it in a future update

Also, while I’m here, Euclidean rhythms wouldn’t go amiss either