-Add: License file.
-Remove: PacketField is not implemented differently.
-Change: remove unused import.
-Add: as_dict() helper for Packets.

This returns the data of the packet as a dict; only fields defined will
be returned.
-Fix: ClientQuit was using the format of ClientError.

.. and while at it, we'll add ClientError.
-Change: allow StructField classes to repeat.

This way, we can encode certain data, like the Shareholder data for
companies, in 1 field.
-Add: RepeatingField, for when we loop a fixed amount of time.
-Add: Some more packets.