eliminated model->meshlist, replaced with an embedded model->surfmesh to cut down...

eliminated model->meshlist, replaced with an embedded model->surfmesh to cut down on pointer indirections, this also eliminated surface->groupmesh
some minor optimizations of code to keep track of ent->model in a local variable rather than dereferencing ent every time

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@6212 d7cf8633-e32d-0410-b094-e92efae38249