This program make weight and balance calculation of aircraft.

The first command-line argument will be the aircraft type. If it contains
a slash then it is the filename path otherwise it look in its own
directory for the data. The rest are given parameters, with name and
equal sign and value; the aircraft data files have the same format. The
output will be the table of values which you can then send to the printer
if you want a printout.

Currently not implemented features:
- Lateral balance
- Plotting
- Minimum weight
- Valid ranges
- Helicopters
- Different limit for landing and takeoff
- Auto fuel calculation
- Calculation of adjustment needed
- More than two rows of seats
- Better documentation