Refactor packet encode/decode
There should be encode/decode macro like this:
PrrtPacketField_encode(data_payload, buf_ptr, prrtPacketLength_t, packetLength, htonl);
PrrtPacketField_decode(feeback_payload, dstBuffer, prrtTimedelta_t, btl_pace, ntohl);
// encode
prrtPacketLength_t *packetLength = (prrtPacketLength_t *) buf_ptr;
*packetLength = htonl(data_payload->dataLength);
buf_ptr += sizeof(prrtPacketLength_t);
// decode
prrtTimedelta_t * btl_pace = (prrtTimedelta_t *) dstBuffer;
feedback_payload->btl_pace = ntohl(*btl_pace);
dstBuffer += sizeof(prrtTimedelta_t);