Small default FocusItemStyle improvements.
Adds necessary actions and tests.
FocusItemList and LinearLayout improvements.
Renamed FramesTimelineTest to AnimationEditorTest.
Adds AnimationEditor.
Convenence methods and attributes.
FrameWidget refactoring (duplicate, delete, correctly managing the time...).
Adds PreviewView, a view that holds an FramesComponent and displays/updates it when the model changes.