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.
Reject invalid frequencies from apt.dat in the loader, and fix
25Khz encoding to be the exact value (i.e round frequencies ending
in 20 and 70 to 25 and 75)
Fix ATCdialog to show 3 digits of comm radio frequency at all times,
and remove its rounding-conversion.
Finally, expand the tests to capture the new behaviour. Test for
EPLL is disabled for now because it contains an invalid frequency.
Fix a bug where we would copy-assign a PropertyObject, when we
actually wanted to copy the value.
Thanks to Sascha Reißner for tracking the problem down.
Revert this change - I will re-add the unit-tests again, but we need
a different approach for 8.3 stations, than what I did here.
This reverts commit 91cc83abb5.
In 8.3 mode, ensure that 25 and 75Khz channels can be tuned using the
abbreviated syntax (eg 118.02 for 118.025).
As part of this, add test coverage of the CommRadio for basic and 8.3-
mode operation.
