majalan

Copperbox revision 3035.

I've added PhraseMonad which unifies the Phrase, Advance and Legato note list objects. The key insight is to represent current position (strictly speaking a delta, not a position) independently of accumulated time-span. Phrase events don't update the current position, Advance events update the position with there exact length (i.e. end-to-end placement) and Legato events update the position by an independent symbolic duration so sustain can continue as the next note starts.

At the moment I've got the API of the new Phrase object to work out, so it isn't integrated into the EventList module.