[BUG] WINGAREA = 0 crashes YSFlight

[decaff42]

YSCE Build Number
Upstream, YSFlight 2015, OGL2

System Specifications
Mac OS

Describe the bug
When the DATVAR WINGAREA is set to 0, no mater what altitude the aircraft is spawned at, it will die. The player will be presented with a 100% black screen.

To Reproduce

1. Set Wing Area to 0.0
2. Fly Airplane

Expected behavior
An error should be generated or YSCE should handle situations where invalid DATVAR entries are encountered.
For WINGAREA in particular, if YSCE detects that it is set to zero, it should default to 1.0m^2

[decaff42]

Suggest changing the following:
[src/vehicle/fsairplaneproperty.cpp, line 329] Change to chWingArea=1.0;
[src/vehicle/fsairplaneproperty.cpp, line 8383] Add new line to check if res == 0 and if so, set res = 1