Add 404 error handling

inc/main.php

@@ -173,7 +173,12 @@ abstract class Main extends PhpObject
 	}
 	
 	public static function goTo403() {
-		header('HTTP/1.1 403 Forbidden');
+		http_response_code(403);
+		exit;
+	}
+	
+	public static function goTo404() {
+		http_response_code(404);
 		exit;
 	}
 }