Added: Effects & shaders!!

This new demo adds basic support for Quake3-like shaders. I am now working on the missing features.
With shaders you may change the settings of the rendering pipeline to achieve amazing effects. Take a look at q3ase (Quake 3 Arena Shader Editor) at http://users.chello.be/sf15772/q3ase.html and learn how to make your own special effects
(NOTE: only a subset of the entire funcionality will be implemented for the time being)
We also removed collision detection routines that slowed down everything (they will be
added again later), so performance should be increased... even with shaders working!