On NPF connection state handling

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

Hi,

I have made some adjustments to the NPF connection state handling in
the NetBSD -current.  The state behaviour can now be configured using
the configuration-level parameters -- please see explanations in the
manual pages at the following locations:

- npf.conf(5) manual page, the "Stateful" section.
- npf-params(7) manual page, the section on the 'state.key' parameters.

Let me know if you have any questions or if you would like to suggest
wording improvements to these sections.

Thanks.

-- 
Mindaugas