Update language files, add de_x_sie, and clean up files

migrations/v210_rc2.php

@@ -11,7 +11,7 @@ namespace board3\portal\migrations;
 
 class v210_rc2 extends \phpbb\db\migration\migration
 {
-	static public function depends_on()
+	public static function depends_on()
 	{
 		return array('\board3\portal\migrations\v210_rc1');
 	}