finished model/map rendering merge, model renderer has been completely removed

finished model/map rendering merge, model renderer has been completely removed
model_t num_textures now lies a bit to keep things simple, it equals num_surfaces on models, even if there are multiple skins, in data_textures these extra textures really do exist even though num_textures does not count them (this was done so that UpdateAllTextureInfo won't crash trying to index later skins on the later skins themselves)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@5277 d7cf8633-e32d-0410-b094-e92efae38249