micro-tones in TabStaff are now printable. Unless the chosen
string-tuning will allow it, this feature is disabled for
FretBoards.
- changing determine-frets (adding an optional argument) and
fret-number-tablature-format
- adding a regtest with quarter-tone-string-tuning
- documenting it in Documentation/notation/fretted-strings.itely
and Documentation/changes.tely