Changed test settings
Removed an object instantiation, and replaced it with reuse of an existing object.
Added a new scene for testing performance to SceneLoader.
Cleaned up code and comments.
Attempted to reduce the overhead of the DiffuseMaterial.
Removed an old normal interpolation method from Triangle.
Added a mutiple-operation-mutation method for adding multiplied colors to Color.
Modified the sub-pixel ray iterator of ProgrammableCamera to drop all aperture calculations when only sampling one pixel per ray.