* Use "const string&" rather than "string" in function calls when appropriate.
* Use "const Point3D&" instead of "Pint3D" in function calls when appropriate.
* Improved course calculation in calc_gc_course_dist()
* Safer thread handling code.
Vassilii Khachaturov:
Dont use "const Point3D&" for return types unless you're absolutely sure.
Erik Hofman:
* Use SGD_(2)PI(_[24]) as defined in simgear/constants.h rather than
calculating it by hand every time.
KEMT (w120n30 scenery), and you will have to set the property
/sim/ai-traffic/enabled to 'true' to see the other plane (and tune
comm1 to 121.2 to hear the other plane's radio calls).
