renamed varray_ arrays to rsurface_array_, and they are no longer used outside the...

renamed varray_ arrays to rsurface_array_, and they are no longer used outside the surface rendering code, additionally they are now dynamically resized (saves a little memory)
audited a lot of memory allocations and fixed a few significant leaks
removed Host_ClearMemory as it was causing several memory leaks, and split cls.mempool into cls.levelmempool and cls.permanentmempool, cls.levelmempool is now emptied each level load (this also fixes those same leaks)
merged r_shadow_mempool into r_main_mempool

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@6154 d7cf8633-e32d-0410-b094-e92efae38249