Feature 1255 : improve sql

Replace in queries LIMIT N,M by LIMIT N OFFSET M

git-svn-id: http://piwigo.org/svn/trunk@4331 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/rating.php

@@ -176,7 +176,7 @@ SELECT i.id,
   WHERE 1 = 1 ' . $page['user_filter'] . '
   GROUP BY r.element_id
   ORDER BY ' . $available_order_by[$order_by_index][1] .'
-  LIMIT '.$start.','.$elements_per_page.'
+  LIMIT '.$start.' OFFSET '.$elements_per_page.'
 ;';
 
 $images = array();