Writes the stream based on the messages sent to it. This overlaps with the SimpleStreamFormatter, but was needed to support streams. The SimpleStreamFormatter took a QDataSet and formatted it. This formats based on the callbacks. Note the library was poorly designed, and this is pretty simple because most of the hard work is buried within the StreamDescriptor. StreamDescriptor should be simplified, and the code should be moved to here.
create a stream descriptor packet. TODO: createPacketDescriptor. See SerialStreamFormatter for examples of how this would be done.