Rename CCEffect initWithUniforms: vertexUniforms: ... to initWithFragmentUniforms: vertexUniforms: ...
CCEffectRenderer cleanup - Move post-render composite into the renderer

This code was previously duplicated in CCSprite and CCEffectNode but now it lives
within CCEffectRenderer.
Fix nil effects on CCEffectNode

Just render the node's children with no effects.
Handle empty effect stacks

If the renderer is passed an empty effect stack it just draws the sprite as if no effect was
applied at all.
Merge remote-tracking branch 'origin/develop' into develop