Issue #344: Release session lock before embedding

embed.php

@@ -71,6 +71,9 @@ try {
 $context = context_module::instance($cm->id);
 require_capability('mod/hvp:view', $context);
 
+// Unlock session during embed.
+core\session\manager::write_close();
+
 // Set up view assets.
 $view    = new \mod_hvp\view_assets($cm, $course, ['disabledownload' => $disabledownload, 'disablefullscreen' => $disablefullscreen]);
 $content = $view->getcontent();