Exclusion list

Hey I would love to see this asap.
An exclusion list so that blogs that use comments for archiving purposes don't get closed. Exclusions can be added in the mod admin screen.

the cron run can do something like

// knock it out
$qstr = "UPDATE {node} SET comment = 1 WHERE (created < $oldest_allowed) ".
_comment_closer_node_select($process_node_type_list) . " AND (node) NOT IN (SELECT (node) FROM comment_closer_exclude)";