- Support internal relayout, that is a relayout caused by internal layout changes, like subnodes re-arrangement and/or subnodes' size change. The constrained size applied to root node is unchanged.

- Update Kittens example to show how internal relayout is done.

AsyncDisplayKit/ASDisplayNode.h

@@ -506,7 +506,18 @@ typedef CALayer *(^ASDisplayNodeLayerBlock)();
 @interface ASDisplayNode (UIViewBridge)
 
 - (void)setNeedsDisplay;    // Marks the view as needing display. Convenience for use whether view is created or not, or from a background thread.
-- (void)setNeedsLayout;     // Marks the view as needing layout.  Convenience for use whether view is created or not, or from a background thread.
+
+/**
+ * Marks the view as needing layout. Convenience for use whether view is created or not, or from a background thread.
+ * 
+ * If this node was measured, calling this method triggers an internal relayout: the calculated layout is invalidated,
+ * and the supernode is notified or (if this node is the root one) a full measurement pass is executed using the old constrained size.
+ * 
+ * Note: If the relayout causes a change in size of the root node that is attached to a container view
+ * (table or collection view, for example), the container view must be notified to redraw. 
+ * In case of table or collection view, calling -beginUpdates and -endUpdates is enough.
+ */
+- (void)setNeedsLayout;
 
 @property (atomic, retain)           id contents;                           // default=nil
 @property (atomic, assign)           BOOL clipsToBounds;                    // default==NO