- fix: quick search error if the query term contained " or '

- optimized sql query in sync_users (called every time on admin page) - a lot faster when #user_cache_categories is big
- added function Template->delete_block_vars (opposite of assign_block_vars)

git-svn-id: http://piwigo.org/svn/branches/branch-1_7@2094 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/include/functions.php

@@ -1159,7 +1159,7 @@ SELECT user_id
   foreach ($tables as $table)
   {
     $query = '
-SELECT user_id
+SELECT DISTINCT user_id
   FROM '.$table.'
 ;';
     $to_delete = array_diff(
@@ -1989,4 +1989,4 @@ UPDATE '.USER_CACHE_TABLE.'
   pwg_query($query);
   trigger_action('invalidate_user_cache');
 }
-?>
+?>