Convert menu link deletion to Deletion API

A follow-on to: http://drupal.org/node/151583 for concerns not resolved by that patch.

This conversion is waiting on http://drupal.org/node/151583 and http://drupal.org/node/146425

The goal is to convert function menu_link_delete() and it's help function to use the deletion API. All the queries need to be added to an open deletion package, rather than being executed directly. For example, in the menu or book module when deleting a node, the deletion of associated menu links should be part of that node's deletion package.

In addition, menu module needs to open a deletion package and define the confirm form for deleting a link using the Deletion API.