added a Mod_BuildNormals function to accelerate vertex lighting which doesn't need...

added a Mod_BuildNormals function to accelerate vertex lighting which doesn't need texture vectors
moved vertex blending function from gl_models.c to model_alias.c and renamed accordingly
model loader now compiles frame zero into raw arrays because most models are not animated, this speeds up non-animated models, and anything else idling on frame 0, this eliminates vertex processing in many cases

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@4535 d7cf8633-e32d-0410-b094-e92efae38249