Quake III Arena Cell Shading 1.0

Quake III Arena Cell Shading is a modification for Quake III Arena which makes the game look like a painting or cartoon.
Two techniques are used. The default one (Kuwahara filtering) simplifies the texture a bit, and the second one removes the texture, so it looks plain.
Enhancements:
- This release added an alternative cell shading algorithm (white texture).
- Rocket smoke trails and sprites like text and buttons are not cell shaded.
- Mirrors now work as expected.
- A sky/depth bug was fixed.
- A new makefile was provided, which should simplify building under Linux. r_celshadalgo and r_celoutline variables were added.