The fourth assignment requires writing a ray tracer.  Minimally,
shadows and specular highlights should be implemented.  One
additional feature (such as mirror reflections or solid textures)
also needs to be added.

Each student is required to submit two images.  One is an image
created for a scene created by the student's.  The other is for
a scene we provide.  In the scene we provide, there are 5 spheres 
and one regular solid.