Texture stubs
Plain uniform color texture
Objects have a Texture, not a simple Color
Make Object's texture property a pointer to allow for polymorphism
Objects use intersection data to get color from texture
Texture coordinates are set during intersection computation
Texture coordinates computation basics (not correct)
Fix freeing an unallocated object
Basis for grid texture
Textures test scene
Add current render example
Merge branch 'master' into textures

Conflicts:
	Makefile
	src/main.cpp
Merge pull request #22 from merlinND/textures

Programmatic textures
Merge branch 'master' into image-read

Conflicts:
	Makefile