- Fixes ferry flights causing errors when "Nothing" is not available
- Logs a warning when a frontline stance is suddenly no longer available and uses defense stance as fallback which used to be the default. An investigation is still required to determine the cause of this...
This allows unique identification across saves. The front-end needs to
be able to differentiate the first carrier in game A and the first
carrier in game B, but because carriers (and other non-airfield CPs) are
assigned IDs sequentially, collisions were to be expected. The front-end
can't tell the difference between a reloaded game and a new turn, so we
need to ensure different IDs across games.
This is a handy cleanup anyway, since callers constructing CPs no longer
need to manually track the CP ID counter.
Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2078.