Bala

Copperbox revisions 140 & 141.

Revision 141 adds changes to SymBase that were missed in 140 (140 will note compile).

The final tagless versions (SymLilyPond and SymAbc) can now generate output for their respective formats - the files DemoSymLy.hs and DemoSymabc.hs have tentative examples. There is still a lot of work to do, but to me this feels like a milestone.

I've added a datatype MeterFraction that represents fractions that shouldn't be normalized. Previously meters were represented by the Rational datatype from the standard libraries , but this normalizes fractions - 4/4 automatically becomes 1/1. This is not the required behavior for time signatures.