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
fix #24102: pedal sounds in wrong instrument

pedal was always being applied to top part of score rather than the part
actually applied to
update bravura/smufl
fix #23366: yet another left over CamelCase...
handle channel changes too
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.
fix #23999: instrument change produces incorrect mixer details
fix #24245: slurs in voice > 1 attach to wrong voice on load
update build to Qt 5.2.1 for Windows, use the standard paths for Qt and MinGW
add install plugin manual
Qt 5.2 is not required for Windows, strictly speaking only 5.1 is required by the code, QT_MIN_VERSION should reflect this. Use online installer Qt path on Windows.
UI improvements
making fretboard distcance to staff consistent

with other similar settings by using negative values if above staff