title: Alternative to deprecated get_io_service()
body: <p>Asio v 1.11. The doc says that <code>basic_stream_socket::get_io_service()</code> member function is deprecated and <code>get_executor()</code> must be used instead. But the latter returns <code>executor</code> not <code>io_service</code>.</p>
  
  <p>How to obtain reference to the <code>io_service</code> object used by socket to construct another one?</p>