Added an admin notice that explains how to get to the menu editor page. This notice will only show up on new installations and will automatically disappear once the user visits the plugin page.
 
 Rationale: Now and then, I get support requests asking where the settings page is. This is more common with Multisite installations where new users may have a hard time finding the menu editor because it won't show up in the network admin. 

git-svn-id: https://plugins.svn.wordpress.org/admin-menu-editor/trunk@796612 b8457f37-d9ea-0310-8a92-e5e31aec5664