CCEffectNode - Fix a bunch of sizing issues and add tests for them

- Refactor CCRenderTexture's create method into create and createTextureAndFboWithPixelSize. In CCEffectNode, override the create method so pixel size is computed correctly. This fixes effect node's parent relative sizing while leaving render texture the same (because render texture needs even more changes that I don't want to tackle right now).
- Override setContentSizeType on effect node so it also marks the content size as dirty when it changes.
- If content size has changed since the last visit, destroy any allocated resources and recreate them (as CCRenderTexture already does).
- Pass the content size in points to CCEffectRenderer from sprite and effect node.
- Add a bunch of effect node sizing tests.

**Update**:
- Fix handling of sprite color and opacity when combined with effects.
- Fix handling of clipping nodes as children of effect nodes.
- Fix effect node resizing when an effect node's size is parent relative and the size of a parent changes.
- Add tests for all of this.