Bala2

Copperbox revision 766.

I've revised RhythmPattern to be a list of events (notes) or rests. Events and rests have a duration, this means the new RhythmPattern has more information than the previous one. The previous version tried to synthesize the duration of events (effectively by zipping a list of durations into the onset list); it is easier to have them as part of the data structure.