Implement relevance ranked boolean searching on a full text index of

item and comment data.  Whew!

It's not pretty yet.  And you have to manually update the index
currently in admin/maintenance.  But it works.

modules/comment/helpers/comment_installer.php

@@ -58,6 +58,9 @@ class comment_installer {
 
   static function uninstall() {
     $db = Database::instance();
+    $sql = "SELECT `item_id` FROM `comments`";
+    module::event("item_related_update_batch", $sql);
+
     $db->query("DROP TABLE IF EXISTS `comments`;");
     module::delete("comment");
   }