Bala

Copperbox revision 350.

The latest set of changes for Bala - which are notable for commenting out most of Saturday's work.

I haven't really worked out the composition mechanisms for Bala. Obviously I'd like to build bigger pieces from smaller ones - sections from phrases, phrases from motifs, but I'm missing something to do this. The example SambaBaiao is illustrative - ideally I'd like the tap pattern to play a different pitch or even a chord to the foot pattern that it overlays. Does this mean I should transform both patterns before I overlay them, or preferably, can I transform a complete structure once it is built?

At the moment I really just have fmap / functor transformation so every element within a container is similarly transformed - what I would need is traversal control to change say just the top motif in an overlay (the focused shape-contents traversals have capabilities above fmap but I need something else here).