vuurmuur: Make portforward rules work.

vuurmuur: Make portforward rules work.

The Portfw rules did not work, since vuurmuur does not know the concept
of local networks and produced FORWARD rules in place of INPUT rules. We
emulate this behaviour by giving the firewall a virtual interface for
each vserver on the world.inet network. This needs splitting the Portfw
rules into a normal Dnat rule and a hacky Accept rule, which gets in_int
set.