- images.file categories.permalink old_permalinks.permalink - become binary

- session security improvement: now the sessions are valid only for originating ip addr (with mask 255.255.0.0 to allow users behind load balancing proxies) -> stealing the session cookie is almost a non issue (with the exception of the 65536 machines in range)
- metadata sync from the sync button does not overwrite valid data with empty metadata
- other small fixes/enhancements:
 - added event get_category_image_orders
 - fix display issue with redirect.tpl (h1/h2 within h1)
 - fix known_script smarty function registration
 - query search form not submitted if q is empty
 - better admin css rules
 - some other minor changes (ws_core, rest_handler, functions_search...)

git-svn-id: http://piwigo.org/svn/trunk@2521 68402e56-0260-453c-a942-63ccdbb3a9ee

include/functions_category.inc.php

@@ -258,8 +258,9 @@ SELECT galleries_url
 function get_category_preferred_image_orders()
 {
   global $conf, $page;
-  
-  return array(
+
+  return trigger_event('get_category_preferred_image_orders',
+    array(
     array(l10n('default_sort'), '', true),
     array(l10n('Average rate'), 'average_rate DESC', $conf['rate']),
     array(l10n('most_visited_cat'), 'hit DESC', true),
@@ -269,9 +270,9 @@ function get_category_preferred_image_orders()
     array(
       l10n('Rank'),
       'rank ASC',
-      ('categories' == $page['section'] and !isset($page['flat']))
+      ('categories' == @$page['section'] and !isset($page['flat']))
       )
-    );
+    ));
 }
 
 function display_select_categories($categories,