Enabled for bluefor modern, since they ought to have GPS but seemingly
don't.
This change does nothing until https://github.com/pydcs/dcs/pull/102
lands and we update to it.
The UI sets these to the proper enum types; only the default is wrong.
Fix the default and clean up the associated code.
Note that this does minorly break save compatibility and alters default
behavior, since previously we were ignoring the default option. Ignoring
the default looks unintentional since there is no explicit "don't force
this option" setting in the UI.
Existing saves can be fixed simply by changing this option to something
else and then back.
