Variety of changes to the way we do user editing:

1) Allow admins to edit the admin bit of other admins
2) Don't allow admins to delete themselves (partial fix for ticket #213)
3) Inline user::update().  Don't do form processing in helper methods!
4) Inline user::_get_edit_form() so that we can treat edit forms differently.
   Trying to hard to make common functions makes for weird edge cases.

modules/user/models/user.php

@@ -21,10 +21,10 @@ class User_Model extends ORM {
   protected $has_and_belongs_to_many = array("groups");
 
   var $rules = array(
-    "name" => "required|length[1,32]",
+    "name" => "length[1,32]",
     "full_name" => "length[0,255]",
     "email" => "valid_email|length[1,255]",
-    "password" => "required|length[1,40]",
+    "password" => "length[1,40]",
     "locale" => "length[2,10]");
 
   public function __set($column, $value) {