CCEffects - Fix compiler warnings

- CCShaderUniformPreviousPassTexture should be "NSString * const" not "const NSString *". The former
gets rid of a compiler warning when passing the constant as a parameter and it also matches string constant
declarations in Apple's APIs. Should we update all the other shader constants (and maybe all constants
everywhere)? If so that's another change for another day.

- Stop using the deprecated version of [CCRenderState initWithBlendMode...]
CCEffects - Fix compiler warnings on OSX

- One of this is an unused variable warning so that's just commented out.
- One was a legitimate bug caused by a copy-paste error.
CCEffects - Fix compiler warning and add an assert for an unsupported situation

We don't currently support effects with multiple inputs* so assert that we're not getting
them. Because of this limitation we only need one temporary variable when stitching effects
together. Fix a compiler warning where we had a loop over all inputs that we don't need.

*Note: In this context, the word "input" means some color value that is potentially the output
of a preceding effect in an effect stack.
CCEffects - Fix compiler warnings / strong reference cycles

Refer to the uniform translation table via weakSelf not self. This fixes a bunch of strong reference
cycles and also fixes a couple unused variable warnings for weakSelf.
Merge pull request #879 from thayerandrews/develop

Fix effects in OSX project. Add CCEffectHue.
CCEffectHue - Add a color matrix implementation as suggested by Scott
CCEffectHue - Recompute the color matrix as needed instead of on every draw

This was motivated by the following performance findings on an iPhone 4s.

Original implementation: 26fps / 20% CPU usage
Color matrix implementation: `60fps / 44% CPU usage

Interestingly even removing the matrix computation on every draw, the CPU usage is still
~44%. Since the change doesn't add much complexity I'm keeping it but I'm surprised it
had no impact on CPU usage.
Merge remote-tracking branch 'upstream/develop' into develop