(timeout): New variable.

(timeout_raises_exception): New variable.
(Timeout): New exception.
(expectable): New class.
(expectable.__init__): New method.
(expectable.fileno): New method.
(expectable.fill_buffer): New method.
(expectable.eof): New method.
(expectable.buffer): New method.
(expectable.remove_first): New method.
(impl): New class.
(impl.__init__): New method.
(impl.loop): New method.
(impl.re): New method.
(impl.timeout): New method.
(impl.cont): New method.