Add bullet
Initial bullet support
Use btRaycastVehicle for the car.

Also adds a terribly badly configured wheel as a proof of concept.
Fix gubb-positioning
Add more wheels, tune some parameters.
Fixup Makefile
Fixup compilation (commit?)
Merge branch 'master' into bullet

Conflicts:
	Makefile
	src/main.c
Add and use linmath.h

From https://github.com/datenwolf/linmath.h,
license is "DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE"
Render something at the bottom of a gubbe
Tune the car a bit
Move everything around
Add some help functions for new gl functionality and add glew
as a dependency.
Render the car using a shader.

Nothing fancy for now, and still letting openGL handle
the matrices for us.
Render gubbar using shaders
Render the map using shaders
Render the HUD using shaders
Use our own matrix math for perspective/view/model
Bump version in shaders. Required to make them work on my Intel-graphics (Sandybridge).
Rely on system bullet instead of carrying our own; update Makefile / Readme