merge r5001 from branch 2.0 to trunk

bug 1469 fixed: I should have permitted an empty feed in URL in r4742


git-svn-id: http://piwigo.org/svn/trunk@5002 68402e56-0260-453c-a942-63ccdbb3a9ee

feed.php

@@ -63,7 +63,7 @@ function ts_to_iso8601($ts)
// |                            initialization                             |
// +-----------------------------------------------------------------------+

check_input_parameter('feed', $_GET['feed'], false, '/^[0-9a-z]{50}$/i');
check_input_parameter('feed', @$_GET['feed'], false, '/^[0-9a-z]{50}$/i');

$feed_id= isset($_GET['feed']) ? $_GET['feed'] : '';
$image_only=isset($_GET['image_only']);