Add CC3Backdrop class as specialized for backdrops.
Support separate RGB & alpha blend functions in materials.

Support separate RGB & alpha blend functions. Support both RGB & alpha blending
from POD files. Fix issue where RGB blending set from POD alpha blending.
CC3DemoMashUp use PPNG for point particles to better blend and fade.
Fix missing point sprite attenuation in CC3LibVertexPositionPointSprite.vsh.
Remove documented support for cocos2d 2.0 & 1.0.1.
Update material blending based on texture opacity.

Add CC3Texture hasAlpha property. Add CC3Material & CC3MeshNode hasTextureAlpha
property. Rename CC3Material & CC3MeshNode hasPremultipliedAlpha property to
hasTexturePremultipliedAlpha. Set CC3Material shouldBlendAtFullOpacity based
on texture alpha, and update blending function.
CC3ResourceNode does not retain CC3Resource.

CC3ResourceNode does not retain CC3Resource.
Replace CC3ResourceNode resource property with populateFromResource: method.
Fix memory leak in CC3EnvironmentMapTexture.

Add NSObject asWeakReference method to create weak references.
Add NSObject & NSValue resolveWeakReference methods.
Update CC3Cache, CC3NodeTransformListeners & CC3TextureFramebufferAttachment
to use this weak reference design. The surface held by CC3EnvironmentMapTexture
now holds a weak reference back to the texture to break the retain cycle.
Add frozen animations.

Add CC3FrozenNodeAnimation subclass of CC3NodeAnimation.
Add CC3Node freezeIfInanimateOnTrack: & freezeAllInanimatesOnTrack: methods.
Add CC3PODResource shouldFreezeInanimateNodes & class-side
defaultShouldFreezeInanimateNodes properties.
Move CC3Node animation methods to CC3NodeAnimations.h/m files as category.
Fix bad reference to backgrounder in template scene class.