New icons
Some strings
Avoid irrelevant enable events in actions
Bug fix in tab widget
Added WidgetUtils to encapsulate common methods to create widgets
Added MirrorSelection action
Added RotateSelection action
Added format tab to scene ribbon
Removed ElementButtons dependency from RepositoryManager.
This facilitates RepositoryManager usage in other platforms.
Renamed UpdateRepository to UpdateLibraryElements action.
Created UpdateLibrary action.
Improved RepositoryManager javadocs.
Merge pull request #568 from RotaruDan/repoChanges

RepositoryManager refactorings.
Merge pull request #561 from anserran/formattab

Added format tab to scene ribbon