Improved settings of CSPs.

Added manifest.json.
Added further security-related HTTP headers.

edit/editHTMLPage.php

@@ -59,7 +59,7 @@ if (isset($task) and $task == "update") {
 
 if (!isset($public)) $public = false;
 
-echo printBackendHead($pageTitle);
+echo printBackendHead($settings, $pageTitle, $pageTitle, $settings['logo']);
 echo printBackendHeader($pageTitle, $translations["help$id"]);
 
 echo '