Add initial material loader
Actually parse a mtl file
Fix small bug in shader where we removed variables but not statements
Get OBJ/MTL interop working with new lighting system
Default to a greenish material if OBJ doesn't have one
Fix bug with float parsing

Some floats had a sign after the exponent, we weren't handling that. I
also took the time to split out common parsing things into a separate
Utils module for our loaders.
Have the light follow the camera
If we don't support the image format, say so.
Try a bit harder
Consume whitespace prior to reading filename
Handle 'map_bump' like 'bump'
Remove compiler warnings
Add JPEG loading
Include possible jpegs from example assets
Small hack for MTL loader

If the MTL file contains zero'd out ambient reflectivity, but then also
gives a texture for ambient reflectivity, then assume that the texture is
the same as the diffuse texture, and set the reflectivity to V3 1 1 1. This
is a fairly small hack, as this should rarely be the case, although I'm worried
that in the future it will cause more problems than it solves.
Flip jpegs in the Y direction prior to loading them to GL.