Improve the automatic fretboard calculation algorithm by changing
the sort order of the notes.
This improvement broke the example on improving automatic fretboards
by specifying a string. I could not find another example, so I
removed the existing example. I wanted to leave the text in case
somebody had the problem in the future.
This improvement also fixed the poor diagram for c:9 in the
predefined fretboards section of fretted-strings.itely