There is a race condition between the time a socket is created and the
time it is initialized (BPF filter pushed, bound to an interface). Indeed,
packets captured in between would still be delivered when reading the socket.
Setting reception buffers to 0 was part of the solution and greatly reduced
the race condition timeframe, but still, packet already captured where actually
not sweeped out. So this also need to be done. Thanks to AGR and Y.E. Jutard.

This server is able to answer to any Read ReQuest, and provide data from
a store or from a joker if the file is not in the store

Fixed DNSStrField.i2m() by truncating chunks of more than 63 bytes because they cannot be encoded (ticket #42)

This automaton accepts any TFTP WRQ request and returns the tranfered file

Most of the initialization is done once for all at the class creation instead of being done at each instantiation
Now the .graph() method can become a class method and can be called directly on a class

Renamed Automaton.cond and recvcond into conditions and recv_conditions to reduce risk of name collision