void silc_client_stop(SilcClient client, SilcClientStopped stopped,
                          void *context);

    Stops the client. This is called to stop the client and thus to stop
    the program.  The client context must be freed with the silc_client_free
    function.  All connections that exist in this client must be closed
    before calling this function.  Connections can be closed by calling
    silc_client_close_connection.

    The `stopped' will be called once the client and all connections have
    finished.  The client may be freed after that.  Note that the `stopped'
    won't be called before all connections have finished.  Setting the
    callback is optional.