renamed normal_vectre to normal_vector
Added tests for KDTree intersection
Implements KDTree::freeAllObj()
fixed bug with camera direction and bug withtriangle/AABB intersection
Properly sampling.
Changed public interface for Raytracer
Adds simple refractions
kdtree handles triangles on the split plane
Added partial reflections on trasparent objects
Separated renderers into different classes

refactored reflection computation

removed namespace

Unified function call names
Adds total internal refraction.