Sync environ.7 and nls.7.

Taken-from: FreeBSD & NetBSD
Remove various unneeded .Pp macro in manual pages (all before .It).
iwn - Resync from FreeBSD 1/2

* Resync all files except the build infrastructure from FreeBSD.
  Next commit will re-port the files.
kernel - minor netproto/802_11 stuff to support iwn re-port

* Bring in some minor changes from FreeBSD which iwn needs.
iwn - Resync from FreeBSD 2/2

* Do a manual run-through and make all DragonFly-specific adjustments
  from the FreeBSD rebase of iwn.

* Tested on a system 76 laptop, basically works (inasmuch as FreeBSD's
  current iwn work works).

* Adds tons of new chips with varying degrees of support relative to the
  original port.