SilcPacketEngine
    silc_packet_engine_start(SilcRng rng, SilcBool router,
                             SilcPacketCallbacks *callbacks,
                             void *callback_context);

    Create new packet engine for processing incoming and outgoing packets.
    If `router' is  TRUE then the application is considered to be router
    server, and certain packets are handled differently.  Client and normal
    server must set it to FALSE.  The `callbacks' is a SilcPacketCallbacks
    structure provided by the caller which includes the callbacks that is
    called when for example packet is received, or end of stream is called.

    The packet engine is thread safe.  You can use one packet engine in
    multi threaded application.