rewrote most of the RSurfShader_ functions to use R_Mesh_Draw_GetBuffer instead of...

rewrote most of the RSurfShader_ functions to use R_Mesh_Draw_GetBuffer instead of R_Mesh_Draw

r_modellights replaced r_lightmodels, r_modellights sets limit on how many directional lights will be shaded onto the model (only the brightest are chosen)

cleaned up lighting code a lot, it is now consistent between static and dynamic light sources, and the light radius has been reduced

unfortunately this commit seems to have slowed down the engine a bit, and I don't know why, it should be a speed gain

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2223 d7cf8633-e32d-0410-b094-e92efae38249