More tweaks to try to catchup to recent pf changes.
pfopt5 part from sthen@

ok henning@ sthen@

lo1, tun0, tun1 don't exist any more. thus, create the interfaces we need for
regress purposes before starting and destroy them afterwards.
lo1 -> lo1000000
tun0 -> tun1000000
tun1 -> tun1000001

ok

lo1, tun0, tun1 don't exist any more. thus, create the interfaces we need for
regress purposes before starting and destroy them afterwards.
lo1 -> lo1000000
tun0 -> tun1000000
tun1 -> tun1000001

ok markus@

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Use merged config file format. The separate NAT loop can go away,
since all files are now loaded the same way. Add regress tests for
invalid ordering of scrub, nat, filter rules