Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

make sure we really don't have a tty when installing rules. This prevents
a flush command from asking a question (you can't see):
If there is no tty associated with the process, this is implied.

MFC after: 1 day

Various spelling and grammar fixes

PR: 44312
Submitted by: Chris Pepper <pepper@rockefeller.edu>
MFC after: 3 days

1) Fix change_rules.sh for the case where firewall_type provides the
name of a file containing ipfw rules.

2) Replace the use of a predictable temporary filename with one
generated by mktemp(1).

3) Only exit with a zero exit status if the rules were updated.

4) Use a pager to view the new rules, not an editor.

I was told by dcs that this script's original author is no longer
interested in FreeBSD and would not wish to review this patch.

Make this really work.

Use ${EDITOR} as claimed.

Source rc.conf and use ${firewall_script} instead of rc.firewall.

Textwidth formatting of comments and text.

PR:
Submitted by: Maxim <maxim@news1.macomnet.ru>

(sorry if I got name/email/committer status wrong :)

Introduce an example script of safe changing of ipfw(8) rules.

I'm sure this can be much improved, but this works fairly well.

PR: 27887
Submitted by: Alexandre Peixoto <alexandref@tcoip.com.br>
MFC after: 1 week