Bala

Copperbox revision 349.

I've added a new module Pulse for working with clave patterns, inspired by Godfried Toussaint's papers:
http://cgm.cs.mcgill.ca/~godfried/publications/banff.pdf
http://cgm.cs.mcgill.ca/~godfried/publications/clave.pdf

The new module is quite preliminary, particularly clave patterns are bit patterns - all attacks have the same unit duration. I haven't yet worked out how I'm going to build rhythm patterns with 'prolongation' from clave patterns, though there is some work in the Pulse module for building patterns where tap (the onset function) has a length.