Most subsystems are now created via the subsystem manager using the global
subsystem registrations.
The FGGlobals add_subsystem() and add_new_subsystem() methods have been removed
as the subsystem manager addition and creation function interface now exceeds
the functionality of these helper functions.
FIx some bugs in computing turnExitPos for fly-over waypoints,
and computing leg course when preceeeding leg is a runway.
In both cass we had an incorrect turnExitPos, so points along
the leg were incorreclty positioned.
Extend the test cases to cover this further.
