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

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

Remove EOL whitespace.

Add net.link.stf.permit_rfc1918 sysctl variable. It can be used to allow
the use of private IPv4 addresses with stf(4).

MFC after: 2 weeks

Fix various broken links in manual pages.

Submitted by: Michiel Overtoom (motoom % xs4all nl)
PR: 159130 159131 159132 159133 159134
159135 159136 159137 158138 159144
Approved by: re (kib)
MFC after: 3 days

Fixed the misplaced $FreeBSD$.

mdoc(7) police: scheduled sweep.

Approved by: re

reject private IPv4 addrs

Obtained from: KAME

Document the fact that these devices are allocated at runtime using
cloning and point to two common methods of doing so.

Ispell sweep of share/man/man4.

mdoc(7) police:

Avoid using parenthesis enclosure macros (.Pq and .Po/.Pc) with plain text.
Not only this slows down the mdoc(7) processing significantly, but it also
has an undesired (in this case) effect of disabling hyphenation within the
entire enclosed block.

Sync with recent KAME.
This work was based on kame-20010528-freebsd43-snap.tgz and some
critical problem after the snap was out were fixed.
There are many many changes since last KAME merge.

TODO:
- The definitions of SADB_* in sys/net/pfkeyv2.h are still different
from RFC2407/IANA assignment because of binary compatibility
issue. It should be fixed under 5-CURRENT.
- ip6po_m member of struct ip6_pktopts is no longer used. But, it
is still there because of binary compatibility issue. It should
be removed under 5-CURRENT.

Reviewed by: itojun
Obtained from: KAME
MFC after: 3 weeks

pseudo-device -> device in kernel config lines. Removed whitespace at EOL.
Reviewed by: joerg, dd

mdoc(7) police: normalize .Nd.

mdoc(7) police: use the new features of the Nm macro.

sync with reality/latest kame

comment out extra .Pp (which is necessary by comment-out of .Bl-.El)

fix partially commented out dangling sentence.

Import stf(6to4 interface) man from KAME.

Obtained from: KAME project