Progress 2

Implemented all features (bugs listed below)
- Blinn-Phong shader isn't working.  Normals are as expected, but the
light*mat is not.
- Some normals appear to be backwards for whatever reason.  Currently
regenerating all the normals using cross products and clockwise
triangles rather than relying on the .obj
- Some triangles create massive scanlines.  I suspect these are caused
by triangles with very large slopes (two point's y coordinates are
nearly equal).  Will be changing the code to fix this later.
- Code is SLOW.  Currently running at 8 fps or so, on cow.obj at half
screen.  It seems that having large triangles actually slows down
performance more since it's not parallelized.

* Backface culling using stream compaction implemented, simply gets rid
of triangles with normals that point towards the positive-z (away from
camera).
* Color interpolation is implemented, seems to make things slow.  Needs
further testing.