added Python binding for material.h classes
added raytracermodule.h header file for declarations
updated car.py demo
added texture.py demo (based on spheres_glass.py)
all remaining 'centre' changed to more common 'center'
added some more const's to material.h
Bugs
====
* Mingw + SSE does not work
Future Plans
============
* UV texturing
* PlanarMap should allow to choose normal axis
* Container should implement Shape interface to allow building hierarchies
* Container should allow local space transformations
* generalization: Camera "shader" (ray generator), surface shader and maybe light & background shaders
* put everything into a namespace
* stochastic oversampling
* absorbtion of refracted rays in dense materials (can be computed using shape distance and some 'absorbance' constant)