Refactor: AnimationPlaybackManager class added to encapsulate plaback logic.
Refactor: AnimationPlaybackManager wired to MainMenu.xib.
AnimationPlaybackManager additional setup in AppDelegate.
AppDelegate's playback logic is unused now.
Refactor: Simplified enabled state for AnimationPlaybackManager.
Removed obsolete code in AppDelegate.
Refactor: renamed SnapLayerKeys file to NotificationNames.
It held only one constant used as a notification name, looking good to hold more.
Added notificaiton name when an animation playback will start.
DeselectAll method added to AppDelegate.
Notification posted when playback animation is started and deslecting all nodes.
Refactor: added const keyword to actual constants.
Refactor: Shortened some methods since they have a better namespace now.
Adding a node to the stage will stop playback animation.
Pasting a node will stop the playback animation.
Merge pull request #515 from NickyWeber/feature/#451_stop_playback_on_actions

Feature/#451 stop playback on actions