unified image loading code a little between renderers. support switching worldmodel in csqc. also associated bugfixes. git-svn-id: https://svn.code.sf.net/p/fteqw/code/trunk@4758 fc73d0e0-1445-4013-8a0c-d673dee63da5
git-svn-id: https://svn.code.sf.net/p/fteqw/code/trunk@4622 fc73d0e0-1445-4013-8a0c-d673dee63da5