Add basic light probes.

Add CC3LightProbe class. Light probes tracked by CC3Scene lightProbes array.
Add light probe shader semantics for uniforms and textures. Add light probes
to standard shaders. Add light probe to CC3DemoMashUp.
Move texture mgmt during drawing to CC3Material.
When binding GL texture to target, unbind all other targets.
Add CC3NodeDrawingVisitor bindEnvironmentalTextures method.
Add CC3Texture textureWithSize:andColor: and textureCubeColoredForAxes
methods as convenience for creating test textures.
Add CC3OpenGL dumpTextureBindings method as convenience during testing.
Simplify the creation of CC3Framebuffer surfaces and CC3EnvironmentMapTextures.

Added a number of convenience init and creation methods to CC3Framebuffer
and CC3EnvironmentMapTexture. CC3DemoMashUp uses new CC3EnvironmentMapTexture
and CC3GLFramebuffer creation methods. Renamed and deprecated a number of
CC3Texture init and creation methods for more consistent naming.
Merge PG fixes.

CC3Texture update texture parameters after generating mipmap.
To avoid clearing vertex content, CC3VertexColors initFromCPODData:fromSPODMesh:
method now doesn't use setter to ensure elementSize set to 4. Fix LogTrace
compilation issues. Light probe changes compatible with OpenGL ES 1.1.
CC3GLSLUniformOverride tracks and updates program and pureColorProgram
uniforms separately.