Some refactoring
MusicXML export of formatting for rehearsal marks
More MusicXML formatting support for lyrics, rehearsal marks and words
update mtest
add xpm icon for older linux distrib
fix #38571: Clef displayed incorrectly after change at beginning of system starting with mmrest
fix #38636: Crash when accessing, or engaged in Continuous View after deleting all measures
Merge pull request #1442 from lvinken/musicxml-font-handling

Musicxml font handling
patches for linux packaging
add explode function