merge yamt-pf42 branch.
(import newer pf from OpenBSD 4.2)

ok'ed by peter@. requested by core@

branches: 1.1.1;
Initial revision

Import PF from OpenBSD 4.2

branches: 1.1.1.1.26; 1.1.1.1.28;
import pf from OpenBSD 3.6. (userland part)

Sync w/ -current. 34 merge conflicts to follow.

Add RCS ID.