use Config-class, check auth first, fixed redirect

users/edit-alias.php

@@ -22,15 +22,15 @@ $rel_path = '../';
 require_once('../common.php');
 $smarty->assign ('smarty_template', 'users_edit-alias');
 
+authentication_require_role('user');
+$USERID_USERNAME = authentication_get_username();
+
 // is edit-alias support enabled in $CONF ?
-if($CONF['edit_alias'] == 'NO') {
-  header ("Location: $Return_url");
+if (! Config::bool('edit_alias')) {  
+  header ("Location: main.php");
   exit(0);
 }
 
-authentication_require_role('user');
-$USERID_USERNAME = authentication_get_username();
-
 $ah = new AliasHandler();
 $ah->init($USERID_USERNAME);