Move "standard" vertex format into Rendering.h

At some point I'll have to rethink the standard vertex format, but for
now "Standard" is (position, normal, tex coord)
ModelLoader base class
OBJModel extends ModelLoader, supports surfaces

- In pursuit of a unified model loading system
- OBJ files can contain multiple surfaces (denoted by the g command), so
I added support for those
- Working on MD3Model next, will probably end up renaming the loaders
Fix brace styles (derp)
MD3Model extends ModelLoader
Unify model loading, display all surfaces

- Removed redundant model loading code for different types of models
- Load all surfaces in a model file and display them all
- TODO: Texturing