Merge branch 'master' of ssh://jomand@git.sv.gnu.org/srv/git/lilypond

Merge branch 'master' of ssh://jomand@git.sv.gnu.org/srv/git/lilypond

* 'master' of ssh://jomand@git.sv.gnu.org/srv/git/lilypond:
  MusicXML: Add sample file for chord names printed above staff
  MusicXML: Update the rest duration sample file with correct multi-measure rest
  MusicXML: Fix small problems with assignment <harmony> <=> voice
  MusicXML: Updates sample files for fretboards
  MusicXMl: Fix fretboard assignment to voices.
  MusicXML: Sample file for fretboards on multi-staff/-voice pieces
  MusicXML: Convert fretboards from MusicXML to Lilypond