Broadcast with coding example

Hi @mortenvp ,

Here is the broadcast with coding example. Basically, it's a sender of UDP packets to 2 receivers. I think later will be nice to create a function for receivers' UDP sockets. I reused the `KodoSimulation` class from the previous example. Also I would like to make some more tests, but you or anyone else can check it out to tell me what could we add.
Here you can simplify the code make making just one ``KodoSimulation::ReceivePacket`` function and then bind in the id of the node in the callback. See the ``MakeBoundCallback`` from ns-3.