Scaling not yet clearly defined in the NMEA protocol about doc_larus

[Simsys]

Some information first:

• The aircraft polar models in the front end and in XCSoar are similar but not the same. XCSoar, for example, does not recognize a pilot weight.
• The definition of the NMEA data sets was based on other existing connections. We cannot start from scratch here.
• There is currently no polar alignment between the front end and XCSoar. This is complex and currently out of scope.

In Detail:

• Ballast: The definition of ballast as a multiple of the usual take-off weight is sufficient.
• Bugs in %: We can expand it to 50%, but i think this is not necessary
• Crew weight: is not known by xcsoar, so we can't exchange it
• Switching between climb and pre-flight: I don't see any point in defining a data set here, as XCSaoar switches this automatically and intervention here may be problematic.

To summarize. I see no need for action here at present. Our goal should be to get the defined functionality up and running. This already covers the most important points.