Switch to Ekmett's linear
Add note about transforms
Add function to change the ambient light

This is kind of a hack because there is no "ambient" portion of a light
in real-life. Really what we want is to specify the amount of extra color
that this light adds to an object irrespective of orientation.
Add a new camera type: Viewer Cam

This camera is fixed about the origin and swivels based on your
mouse movement. I initially thought it'd be good for using as an
.obj viewer camera, but then I realized the light doesn't move with
your camera so you're not really getting the full benefit...
Support mouse button presses
Add initial OBJ viewer
Rotate object instead of camera
Parse OBJs smarter.

- Make sure to ignore the rest of the line once we've successfully parsed a
vert or face.
- Ignore lines after parsing a value rather than before, so that we can still
process EOF if there are ignorable lines at the end of the file