Add User Search option to "Insert Link" Tool when editing News and Pages

It would be very useful to add an additional option to the "Insert Link" tool to allow someone to find users in the system and then add a link for them. A GUI very similar to the one used for selecting users for the restrictions could be added as another tab in the tool, maybe called Users. In our organization the usernames are essentially numeric so it is difficult to make links to users without looking the id up in another system. We are trying to encourage crosslinking, but when its difficult people will rarely do it. If they could search for the user by their last name, similar to the existing restrictions GUI, I believe this will rectify the issue. The created link will be the same behavior as linking to their space if they have one or to their profile if they don't or it isn't visible.