More improvements to UI, added some icons
Added shortcuts control
Added some shortcuts and tiny adjustments in the font
Added undo/redo icons and shortcuts, color change to context menu item disabled
Added notifications systems to actions and commands
- Now, views can listen to "editor events" (a command was executed, an action change
its state from diabled to enable...) and react to them.
Merge branch 'master' of github.com:e-ucm/ead