Bala

Copperbox revision 316.

I've removed quite a lot of rusty code from Bala especially from the Pitch module. I'm trying to get to a small core of types and operations for pitches, intervals, chords, scales etc. - and as pitch is the fundamental one, it needed working first. Pitch has a fairly obvious type - or the requirements for a Pitch type are fairly obvious (octave, pitch letter, accidental or not). The others aren't so obvious, so I've left the rough code for Scale and Chord as it is for the time being.

The Affi & Deco instances for all types have gone into a separate module - I'm not sure if I'll continue with them, they would be nice if I had a custom read-eval-print-loop but they increase the code size of the modules which I'm trying to keep minimized.