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

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

Commit IPv6 support for FAST_IPSEC to the tree.
This commit includes all remaining changes for the time being including
user space updates.

Submitted by: bz
Approved by: re

libipsec and IPsec related apps. (and some KAME related man pages)

Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project