Exclude the Admin Menu From Parent Selection

Issue Link: 
http://drupal.org/node/351249
criticality: 
Critical
Drupal7: 
Open
Task: 
Create a left-sidebar menu link
This happened to: 
Participant 3
Participant 4

Users are often confused by the large number of items placed in the menu before they have even added any items. They often wonder why they can add an item to the administrative section at all.

Implications: 

Users also get thrown off by items like "Main menu" being displayed in two places: as a root level item and under Admin -> Site building -> Menus -> Main menu.