Unicode display of Greek musical notation

In addition to Greek musical characters in their own Unicode block, we need combining characters from a separate block for the length marks (diseme, triseme, tetraseme and pentaseme), and for the raised dot indicating arsis.

mousike supplies an openly licensed font for this purpose. It should be applied only to the musical notation: to keep its size small, it includes upper case versions of signs where Unicode expects you to recycle alphabetic code points as musical notes, but includes no but no lower-case Greek or Latin.