A proposal for aligning note heads to SMUFL conventions.

It should re-enable all the note head functionality as per ver. 1.3, with most (all?) equal results.

- No new glyph added to font(s)
- Existing mscore glyphs have been matched to SMUFL note head symbols:
-- partly on similarity of shape
-- partly on similarity of semantics (in particular most of the noteDo..., noteRe..., ... heads)
- The dropped HEAD_BREVIS_ALT note head group have been re-instated (dropping it was a regression from 1.3)
- fonts/mscore/glyphnames.json has been updated
- fonts/mscore/metadata.json has NOT been updated (I have not understood its contents)


It may be improved incrementally, should the need arise.
Merge pull request #548 from mgavioli/Update_note_heads_to_SMUFL

A proposal for aligning note heads to SMUFL conventions.