Neume

Copperbox revision 1173.

Potential new way of dealing with overlays - concatenated Doc's.

I'm not sure overlays need to be manipulated after all, so it seems that, rather than make them a list of one-or-more "bars" then print them interspersing the overlay separator (&), I can concatenate them as docs with the overlay separator instead.

Note - LilyPond is a bit more convoluted as overlays must form a proper 2D matrix, with the same number of overlays in each bar even if the overlay is empty.