Corrects vertical alignment for stemless notes (semibreves and breves).
First commit too simplistic and didn't work for ledger lines.

Error was in determining stem X pos. Improved.
Merge pull request #184 from mgavioli/Fix_#19809_semibreve_and_breve_vert_misalignment

Fix #19809 Semibreve and breve vertical misalignment