Make a Renderer interface.

RayTracer now implements Renderer. Preparation for the
GlobalIllumination renderer.
Fix triangle normal count. Only do it in finalize.
Remove ambient, diffuse and specular component from light.
Merge branch 'master' of github.com:kovacsv/RayTracer

Conflicts:
	source/raytracer/interface.cpp
Merge branch 'master' into UserInterface