Req for Review: Interface Groups related functions and CARP support in pf

[Jan Lentfer]

Hi all,

please review especially the first link.

http://gitweb.dragonflybsd.org/~lentferj/dragonfly.git/commit/f287ec34e667f31d21d85fc88a03f85743068f1d
http://gitweb.dragonflybsd.org/~lentferj/dragonfly.git/commit/c9809d142e1e05d36aaf2ce5a135ec9e2f2dd317 
(very short patch :-)

Sascha Wildner pointed out to me CARP support in if_pfsync.c was 
implemented but not activated, yet.
So I did that, which led to importing a lot of still missing interface 
groups related functions.

Jan