Bug 354

I am playing with my gjc/ns-3-pyviz branch and been noticing inconsistencies wrt. tracing and promiscuous mode.  I am sorry I did not catch this sooner, but better late than never.

- CsmaNetDevice does not generate any trace when a packet is received promiscuously (PACKET_OTHERHOST).  In my branch, I experimentally added a new PromiscRx trace and generate it for all packets but only when there is a promiscuous mode protocol handler:

      if (!m_promiscRxCallback.IsNull ())
        {
          m_promiscRxTrace (originalPacket, packetType);
          m_promiscRxCallback (this, packet, protocol, header.GetSource (), header.GetDestination (), packetType);
        }

- Wifi does not have a separate protocol handler for promiscuous mode, instead unconditionally always generates Rx trace for all packets, even PACKET_OTHERHOST;

- PointToPointNetDevice does not even care about destination addresses, it's like it is permanently in promiscuous mode.

I think it would be better to converge.  On one hand, I can probably manage to not use a PromiscRx trace, by looking at the netdevice and checking if it is part of at BridgeNetDevice (once a proper BridgeNetDevice API is provided for that).  On the other hand, doing so would be more complex in terms of code and probably less efficient computationally than listening to a PromiscRx trace.

Opinions?