Adds a new state to the view statechart, SC.CoreView.ATTACHED_SHOWN_ANIMATING. This state is for views that are manually animated via a call to `animate` when in the ATTACHED_SHOWN state and is used to cancel manual animations if a view is hidden or removed, which would cause the animation callbacks to fail to trigger. Also prevents animate from running on views that are not visible in the window. Also fixed double invokeNext call when runAnimationCallback is wrapped in an invokeNext.