added entity caching stats in graph

optimized logic for animcache and dynamic batching
optimized r_shadows code which was often casting shadows from entities
it did not animcache, and these entities didn't need to cast anyway,
imposed an artificial limit of 1024 entities in r_shadows code...
now exactly determines if models are animated at load (except iqm which
is trusted), and the isanimated flag is not needed for animating a
skeletal model with skeletonobject

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@11901 d7cf8633-e32d-0410-b094-e92efae38249