Finish base port of vertex array classes:

* CC3VertexTextureCoordinates
* CC3MatrixIndices
* CC3VertexWeights

Work on port of CC3MultiTextureConfigurable in-built shader

* porting of shader from HLSL to GLSL to support material/lighting effects
* porting of base functionality of all the relevant higher-level classes (CC3Light, CC3MeshNode etc.) that connect to the shader's uniforms
* updating sample app to showcase materials