Standardize and Secure Volpiano Methods Don't Account for Syllable-Independent Notes in CWMN

[kemalkongar]

The two methods, which aim to make it reliable to compare volpiano strings as long as the underlying notes are correct, do not account for syllable-indepenent notes in CWMN files we've come across in the Andrew Hughes repository.

I haven't done anything with the methods themselves as I've got a hunch that this will be resolved in some of the prior methods, such as convert_mei_volpiano() or export_volpiano(). That being said, it's still important to keep in mind. If these notes appear on the manuscripts, we'll have to append them to the end of the standard and secure volpiano outputs.