CWMN MEI conventions

[annamorphism]

The documentation currently says that this follows the conventions of the Andrew Hughes MEI files, including that
"Syllables are preceded by their notes
All notes must have syllables after them"

However this does not actually seem to be the convention of those files: the syl are preceded by the first note of that syllable, and then followed by their remaining notes. Final notes of a chant might not have a syl element after them, if they are part of a multi-note syllable.

[kemalkongar]

This would be in line with our suspicion that the conversion for Andrew Hughes, and the syllable-indpendent note issue, is incomplete. We need some way of standardizing syllable-note mapping so this is something to investigate further.