Add CC3ShaderProgram init methods with default semantic delegate.

Add CC3ShaderProgram init methods with default semantic delegate.
Minor renaming of other CC3ShaderProgram init methods. Bump map shaders
auto-selected only if material has at least two textures.
Create partial animation track from existing track.

Add CC3NodeAnimationSegment class to support animating a segment of a full
animation. Add CC3Node methods to create animation track from segment of existing
animation track. CC3DemoMashUp add dragon example of animation blending.
Rebrand cocos3d logos and launch images.

Rebrand cocos3d logos and launch images. Refactor cocos3d templates.
Fix compilation issue with GL VAO call under OpenGL ES 1.1.
Move template project icons and launch images to Xcode groups.
Pre-warm shader programs after linking to avoid transient freezes.

Add CC3ShaderProgramPrewarmer to prewarm each shader program after linking by
drawing a dummy mesh to force lazy compile in GL engine. Populate CC3GLSLUniforms
with appropriate default values. Add CC3ShaderContext shouldEnforceCustomOverrides
property to allow context to ignore unknown semantics, and substitute the default
value. Support setting 2x2 matrix in uniform via a CC3Vector4.

Add CC3Texture samplerSemantic property to clarify texture semantic type. Populate
shader with correct texture defaults when shader supports both 2D & cube-map textures,
and either one or both are missing in material. CC3Material textureForTextureUnit:
method returns nil if texture unit not present. CC3NodeDrawingVisitor init shader
matrices with identity matrices if not populated by scene.