CCEffects - Stacking bug fixes plus test additions

- Fix a bug in varying name mangling. Varying arrays were losing their array-ness and becoming scalars after mangling. This broke bloom and blur in SpriteBuilder (and in other use cases too). This fixes [SpriteBuilder issue #843](https://github.com/spritebuilder/SpriteBuilder/issues/843).
- Fix a bug with stitching of bloom and blur. These effects cannot be stitched to others but their render passes were being altered as if they could be.
- Misc cleanup of the stitching code. Rename a few variables to make their meanings more obvious, change some methods that do not need to be instance methods to class methods instead.
- Add stacks of stacks to the effects test. We now stack glass and hue in one stack, saturation and pixellate in the other, and then we stack these two stacks together on the sprite.
- Add more sprites to the performance test. Some effects were already running at 60Hz with the lower number of sprites which meant that performance improvements could not be detected.