fix #9009
remove drumset checkbox from Mixer
fix #21066, fix #18693, manually merge pull request #165
add predefined sizes to foto mode
fix inspector for lasso (fotomode)
Add support for parentheses before/after chords.

This allows a chord or sequence of chords to be indicated as optional
or alternative, and avoids the need to add the parentheses as text
or extra chords.
Remove obsolete assignment to _userName
Some refactoring, more comments
Tree view for MIDI import operations
Refactoring of quantization
Meter-adapted duration subdivision
Row for all tracks selection in GUI panel
Adapt tst_importmidi to new duration subdivision
fix #21246 reduce text cursor width
fix #21223
fix #21243 allow multiple selection in instrument list
fix #21235 add bracket symbol to notehead master palette
fix #21233 key signature spacing
space flats in key signature closer
better multi selection in instrument dialog