Clean code of lib_notification. Now use cache like other js.

htdocs/core/js/lib_head.js.php

@@ -50,6 +50,11 @@ session_cache_limiter('public');
 
 require_once '../../main.inc.php';
 
+
+/*
+ * View
+ */
+
 // Define javascript type
 top_httphead('text/javascript; charset=UTF-8');
 // Important: Following code is to avoid page request by browser and PHP CPU at each Dolibarr page access.