Finished restructoring the actions and shortcuts.

1) Assign each shorcut to the appropriate widget
2) Change focus policy for all docked windows so that the scoretab doesn't loose focus
unless it's necessary. (except MuseScore Connect window)
For full understanding see this discussion thread:
http://dev-list.musescore.org/Keyboard-usability-and-accessibility-tt7578844.html

	modified:   mscore/accessibletoolbutton.cpp
	modified:   mscore/actions.cpp
	modified:   mscore/data/shortcuts.xml
	modified:   mscore/globals.h
	modified:   mscore/inspector/inspector.cpp
	modified:   mscore/musescore.cpp
	modified:   mscore/palettebox.cpp
	modified:   mscore/scoretab.cpp
	modified:   mscore/scoretab.h
	modified:   mscore/shortcut.cpp
	modified:   mscore/shortcut.h
	modified:   mscore/webpage.cpp