Add cube-map texture loading to CC3Texture & CC3GLTextureCube.

Add cube-map texture loading to CC3Texture & CC3GLTextureCube. Add ability to mix
standard GLSL variable names with effect-defined variable names in shaders loaded
via a PFX effects file. Add cube-map texture to reflective teapot and skybox in
CC3DemoMashUp. Fix iOS 4.0 runtime issue in CC3UIViewController viewDidLayoutSubviews.