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.
Disable GPS::finalLegCourseTest, and one of the View index tests,
so that tests pass successfully.
Also add some default properties so the skeleton traffic tests start
up without crashing.
This required many time related include files, functions, and variables to be
tested for via CMake, and converted to macros via #cmakedefine, so that they
would be automatically set for the test-mktime.cxx file.
