material and texture classes moved to material.(cc,h)
2D texture mappings from textures.cc polished and moved to material.h
add ColourMap class and subclasses to make textures more flexible
two example textures: CheckersTexture and CloudTexture (using Perlin noise)
move shapes to extra source file
add serialize header and source file with common serialization functions
dump/load feature for shapes and kd-tree
fix few minor bugs