Bugs
====
 * Mingw + SSE does not work

Future Plans
============
 * Python binding for material.h classes
 * 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)