CCEffectsTest - Add refraction test
CCEffectsTest - Update refraction test to use a CCRenderTexture for the environment

Using a render texture instead of just a sprite allows for dynamic environments which
makes the effect that much more interesting to look at. Note that getting the texture
coordinate math to work requires setting the anchor point of the render texture's internal
sprite to (0, 0) from its default value of (0.5, 0.5).
CCRenderTexture - Override nodeToWorldTransform for CCRenderTextureSprite

Now that CCRenderTexture's internal sprite is not part of the node graph, it needs some special
code to compute its transform relative to the world. Override nodeToWorldTransform in
CCRenderTextureSprite to accomplish this.