feature 2703: make it easy for plugins to add tabs in admin screens

add a trigger a give an id to each core tabsheets

git-svn-id: http://piwigo.org/svn/trunk@16925 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/help.php

@@ -65,6 +65,7 @@ else
 }
 
 $tabsheet = new tabsheet();
+$tabsheet->set_id('help');
 foreach ($tabs as $tab)
 {
   if ($tab['code'] == $section)