Fix issue #23985.
Furthermore implements deleting all the measures covered by the multi-
fix #23011: change channel broken

Two separate bugs here.  First caused staff text channel changes to be
applied at the wrong time.  Second prevented channel changes to "normal"
from working at all.
fix tests

No longer save explicit "normal" channel name in imported scores.  Also
remove explicit "normal" channel name from Cymbal in instruments.xml.
update importmidi/updateReference script
missed two tests
fix #24349: fret offset text size as style
fix #24349: fret offset text left/right, as style
fix #24494: distance staff to fretboard diagram
minor fixes to the previous 2 commits

minor, as it works without those, but seems cleaner with:
ST_fretNumPos is int -> styleI() rather than stylD()
ST_staffFretDist gets multiplied by _spatium -> styleP() does this for
us, styleD() does not.
UI improvements
making fretboard distcance to staff consistent

with other similar settings by using negative values if above staff
fix chord symbol to fretboard diagram distance
fix #24657: save correct mixer info for instrument change
When adding and instrument to a score with a pickup bar (anacrusis), set the displayed duration to the pickup length and not a full measure rest
fix 6055 - add Ctrl+Shift+0 as command to convert measures containing only rests into full measure rests, even if they are pickup measures
fix 6055 : when setting the measure length, unless the length is equal to the current time signature
fix warnings due to -Wunused-parameters

all happening because the qDebug() calls inside that uses these are
commented out.
change representation of musical symbols in text
show cursor during text editing if text is empty
fix lyrics editing