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

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