Use original filename for Content-Disposition

In most cases this change will have no effect, but noes the response will use the filename that was originally requested. The downloaded filename can be modified to something different as well. E.g. the siteexport plugin will make use of it.

lib/exe/fetch.php

@@ -89,7 +89,7 @@ if (defined('SIMPLE_TEST')) {
     // finally send the file to the client
     $evt = new Doku_Event('MEDIA_SENDFILE', $data);
     if($evt->advise_before()) {
-        sendFile($data['file'], $data['mime'], $data['download'], $data['cache'], $data['ispublic']);
+        sendFile($data['file'], $data['orig'], $data['mime'], $data['download'], $data['cache'], $data['ispublic']);
     }
     // Do something after the download finished.
     $evt->advise_after();  // will not be emitted on 304 or x-sendfile