Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

mdoc: Avoid playing tricks with Ns: If Nm is present in the SYNOPSIS section,
it will be output on its own line. Ns cancels this effect however. This change
is also consistent with the rest of our manual pages.

Remove trailing whitespace per mdoc lint warning

Disussed with: gavin
No objection from: doc
Approved by: joel
MFC after: 3 days

Fix typos and spelling mistakes.

The NetBSD Foundation has granted permission to remove clause 3 and 4 from
their software.

Obtained from: NetBSD

Add support for the optional key in the GRE header.

PR: kern/114714
Submitted by: Cristian KLEIN

- convert to the current style of section 4 man pages
- s/ip.forwarding/net.inet.ip.forwarding/ to match reality [1]

Approved by: keramida (mentor), trhodes (mentor)
MFC after: 5 days
Submitted by: Tom McLaughlin via #bsddocs

s/ifconfig tunnel greN/ifconfig greN tunnel/

Submitted by: ankon@#bsddocs
Approved by: ceri@

Mechanically kill hard sentence breaks and double whitespaces.

Assorted markup, spelling, and grammar fixes.

Add support for WCCPv2. It should be enablem manually using link2
ifconfig(8) flag since header for version 2 is the same but IP payload
is prepended with additional 4-bytes field.

Inspired by: Roman Synyuk <roman@univ.kiev.ua>
MFC after: 2 weeks

mdoc(7) police: overhaul (including adoptation to FreeBSD).

Approved by: re

Add a new gre(4) driver, which could be used to create GRE (RFC1701)
and MOBILE (RFC2004) IP tunnels.

Obrained from: NetBSD