- upload.tpl goes smarty

- start some language cleanup and a small attempt to standardize a bit ...
- debug_language now calls trigger_error instead of echo when missing language key

git-svn-id: http://piwigo.org/svn/trunk@2265 68402e56-0260-453c-a942-63ccdbb3a9ee

include/functions.inc.php

@@ -1084,7 +1084,7 @@ function l10n($key)
 
   if ($conf['debug_l10n'] and !isset($lang[$key]) and !empty($key))
   {
-    echo '[l10n] language key "'.$key.'" is not defined<br />';
+    trigger_error('[l10n] language key "'.$key.'" is not defined', E_USER_NOTICE);
   }
 
   return isset($lang[$key]) ? $lang[$key] : $key;