Change Packet -behaviour.
Parsed values must be accessed through Packet.parsed -dictionary from now on. This fixes problems with Celery etc, when pickling the object.

Added attributes 'destination', 'dbm', 'status', 'sender', 'sender_hex', 'learn' and 'contains_eep' to RadioPacket, not available through Packet.parsed anymore.
Added attributes 'response' and 'response_data' to ResponsePacket, not available through Packet.parsed.
Added attributes 'event' and 'event_data' to EventPacket, not available through Packet.parsed.