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.
Only the in-sim version works for now, the test-suite mode is not
implemented yet. Also the test API will evolve, but should stay close
to what CppUnit defines.
Run a test file by specifying a path to nasal-test : examples will be
added to FGData shortly.
