-Merge from trunk into rend32.

git-svn-id: http://odamex.net/svn/root/branches/rend32@4007 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Revert r3974 for now. It does not always properly clip sprites to drawsegs, allowing sprites to show through floors or walls from certain angles.

git-svn-id: http://odamex.net/svn/root/branches/rend32@4008 b0bcef46-2027-0410-bd56-ab726e9a1d04