now clears stencil to 128 instead of 0, this avoids problems with arbitrary incr...

now clears stencil to 128 instead of 0, this avoids problems with arbitrary incr/decr orders
stencil shadows are now always erased by glClear, never by drawing again, removes r_shadow_erasebydrawing cvar
shadow volumes now have a nudge away from the surface that cast them, this is controlled by the r_shadow_shadownudge cvar (default 1 unit), avoids rare z fighting issues
shadow volume projection distance is now not infinite for alias model volumes, because they are more well-behaved than the world shadows...
msurface_t poly_radius and poly_radius2 removed
now validates elements in more parts of loading (hoped this would reveal a model shadow bug, but it didn't)
Mod_ShadowMesh_AddVertex now uses a hash table search to speed up static shadow volume building (unfortunately this doesn't seem to be the real speed problem)
removed ALLOCMESHINPIECES option from Mod_ShadowMesh code
removed non-PRECOMPUTEDSHADOWVOLUMES option from static shadow volume creation
removed some unused variables

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2597 d7cf8633-e32d-0410-b094-e92efae38249