Merge Branch 'master' Into 'homescreen-ng'

# Conflicts:
#	src/core/specialkey.h
#	src/declarativeitems/griditem.h
#	src/declarativeitems/scalebackgrounditem.h
#	src/editor/charactersviewdelegate.h
#	src/editor/keyboardlayouteditorview.h
#	src/editor/lessontexthighlighter.h
#	src/editor/resourceeditor.h
#	src/models/learningprogressmodel.h
#	src/models/lessonmodel.h
#	src/undocommands/coursecommands.h
#	src/undocommands/keyboardlayoutcommands.h