mdl and md2 vertices are now stored in a different structure called aliasvertex_t...

mdl and md2 vertices are now stored in a different structure called aliasvertex_t, it has all the features of mdl, md2 and md3 formats and simplifies interpolation, it also has precomputed texture vectors for faster realtime lighting.
normals are no longer interpolated if not needed (fake shadows and shadow volumes do not need them)
added VectorM, VectorMAM, VectorMAMAM and VectorMAMAMAM macros to make aliasvertex_t interpolation code more readable

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2652 d7cf8633-e32d-0410-b094-e92efae38249