fix #29776: Solo is not activated on file load
fix #28316
	modified:   mscore/instrwidget.cpp
	modified:   mscore/instrwidget.ui
Add accessibility for instrwidget.ui
	modified:   mscore/instrwidget.ui
Fix #28316 (better)
	modified:   mscore/instrwidget.cpp
	modified:   mscore/instrwidget.ui
Merge branch 'fix_28316' of github.com:andreituicu/MuseScore
Merge pull request #1143 from Igevorse/29776

fix #29776: Solo is not activated on file load
Merge remote-tracking branch 'upstream/master'
Qt 5.2 is now required