- moved timeout handling responsibility from for nat tests from caller to the library
- updated NAT API accordingly
- removed obsolete timeout handling code from gnunet-transport
- updated result callback for nat-test gnunet-transport to not always just report success, but we now actually report the proper result code we got from the NAT API
- updated nat tests

git-svn-id: https://gnunet.org/svn/gnunet@33606 140774ce-b5e7-0310-ab8b-a85725594a96