Some modifications and fixes to support usage of disco in radio sims

TTL and Traffic Class settings added to UpdConnection
DisUnsignedInteger64 replaced with native BigInteger. This gives a lot of missing functionality (such as valueOf, comparator and operators)
Added missing CryptoSystem enum values from EBV
Added Data and SetData PDU implementations
SignalPdu.setData() now takes a copy of the signal data blob. This means that subsequent external modifications to the buffer parameter don't have an effect on the pdu
Ditto with TransmitterPdu antenna and modulation params
Added SpreadSpectrum struct to replace current integer bit field in TransmitterPdu
Added ModulationSystem enum to replace current integer value in TransmitterPdu

openlvc / disco