Refactored score accessibility system

- Removed ElementAccessibilityInfo class
- the info is now constructed in Element::accessibleInfo
- Bar and beat are calculated in the ScoreAccessibility class
- Removed signal from Element class
- the update event is raised in endCmd
- The status bar is cleaned when there is no selection
- The status bar is cleaned when the element is deleted

	modified:   libmscore/accidental.cpp
	modified:   libmscore/accidental.h
	modified:   libmscore/articulation.cpp
	modified:   libmscore/articulation.h
	modified:   libmscore/barline.cpp
	modified:   libmscore/barline.h
	modified:   libmscore/breath.cpp
	modified:   libmscore/breath.h
	modified:   libmscore/chord.cpp
	modified:   libmscore/chord.h
	modified:   libmscore/chordrest.cpp
	modified:   libmscore/chordrest.h
	modified:   libmscore/clef.cpp
	modified:   libmscore/clef.h
	modified:   libmscore/dynamic.cpp
	modified:   libmscore/dynamic.h
	modified:   libmscore/edit.cpp
	modified:   libmscore/element.cpp
	modified:   libmscore/element.h
	modified:   libmscore/fingering.cpp
	modified:   libmscore/fingering.h
	modified:   libmscore/hairpin.cpp
	modified:   libmscore/hairpin.h
	modified:   libmscore/jump.cpp
	modified:   libmscore/jump.h
	modified:   libmscore/keysig.cpp
	modified:   libmscore/keysig.h
	modified:   libmscore/marker.cpp
	modified:   libmscore/marker.h
	modified:   libmscore/measure.cpp
	modified:   libmscore/measure.h
	modified:   libmscore/note.cpp
	modified:   libmscore/note.h
	modified:   libmscore/repeat.cpp
	modified:   libmscore/repeat.h
	modified:   libmscore/rest.cpp
	modified:   libmscore/rest.h
	modified:   libmscore/score.cpp
	modified:   libmscore/score.h
	modified:   libmscore/spanner.cpp
	modified:   libmscore/spanner.h
	modified:   libmscore/text.cpp
	modified:   libmscore/text.h
	modified:   libmscore/timesig.cpp
	modified:   libmscore/timesig.h
	modified:   libmscore/volta.cpp
	modified:   libmscore/volta.h
	modified:   mscore/musescore.cpp
	modified:   mscore/scoreaccessibility.cpp
	modified:   mscore/scoreaccessibility.h
	modified:   mscore/scoreview.cpp