Two minor tweaks

Since you now maintain a {mail_edit_registry} table, I'd like you to join the {mail_edit} table with the registry before retrieving the rows for building the admin/build/mail-edit page. This will allow other modules to store additional template pieces in {mail_edit}, instead of having to create their own table with only a record or two and having to maintain two different access mechanisms.

Also, I'd like to be able to use %variables like

$mailkeys['node-nid'] = t('Notifications for %Pages subscriptions', array('%Pages' => t('Pages')));

for the descriptions. This doesn't work so well when the user tries to edit the descriptions (they contain <em> tags). So I'd remove the tags before placing the description strings into the description edit field. This means the user will lose the emphasizing, but at least he had it when the mailkey first showed up.

The attached patch makes these two changes.