feature:2538 Make a unified messages management

use only $page['infos'] and $page['errors'] vars and and necessary template to all main pages

git-svn-id: http://piwigo.org/svn/trunk@12764 68402e56-0260-453c-a942-63ccdbb3a9ee

include/common.inc.php

@@ -63,7 +63,10 @@ if ( !empty($_SERVER["PATH_INFO"]) )
 // rewriting of language and otherarray values via URI params
 //
 $conf = array();
-$page = array();
+$page = array(
+  'infos' => array(),
+  'errors' => array(),
+  );
 $user = array();
 $lang = array();
 $header_msgs = array();