Change the type of link for comments, various fixes

For sites under spam attack, it is more useful to link back directly to the comment moderation queue than to individual comment edit links.

Conversely, for sites not under attack, it can be useful to maintain the previous behaviour of linking to the comment edit URL.

The attached version (based on previous patches in this queue) adds a setting for this choice for the DRUPAL-5 branch, and also adds phpdocs and fixes a few typos.