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 #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
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.
fix #24574

use flat and sharp symbols in dialogs and tooltips
fix #24635: Wrong octave in note entry after a line break
some more changes for fix #24574

these may need further changes though to become translatable
fix #24624: [MusicXML] Parentheses around a note head is not exported
fix #24289: typo in effects/zita1/mixsect.png
Only ASCII in .cpp files

using \u266d for b and \u266f for #
fix typo