Bala and HNotate

Copperbox revision 330.

Changes to HNotate to get the Bala 'MeterDemo' to work.

I've changed the construction of event lists - the append operator (|#) - so that the first line in a set of overlays continues the 'primary' line of music, rather all the lines in an overlay forking. Also I've redone the fit function for sequences so that it will accumulate zeros with the left-hand result. To illustrate, sectioning the sequence:

(| 5,0,0,4,1,0,0,0,3 |)

by 5 will, should now result in this:

(| (| 5,0,0 |), (| 4,1,0,0,0 |), (| 3 |) |)

Previously the zeros were accumulated to the right, prefixing the next section. This is the wrong behaviour for hyphenating sections, and cause problems for ties. That said, I don't yet account for ties in the midi output module in HNotate so a tied note wrongly sounds twice.