* Child stencils are now applied correctly to the clipping node
Fix incorrect reference count for original program states stored in collection
* Add test for unique child stencils
* Fix comment
This bug has existed since the Cocos2d-x 3.x days. If you set the global z order of a ClippingNode to anything other than the default value, then the ClippingNode fails to clip anything unless the global z order is also set for the Stencil of that ClippingNode. This change makes the ClippingNode._stencil's global z order to follow the ClippingNode's. (Note: you could still manually set the global z order of the stencil as desired to break the clipping. But now the default behavior works correctly and the way one would expect.)
j-jorge