Kneeboard improvements:
* Optional (aircraft specific) metric speeds/distances/altitudes.
* Heading to waypoint.
Fuel still needs to be converted to metric, but good enough for now.
Fixes https://github.com/dcs-liberation/dcs_liberation/issues/915
- removed the map_object_id from the TGO
- add a new TriggerRule with the MapObjectIsDead Condition which adds the map object to the killed_map_objects array in the state.json
- Use the trigger_zone_name as the unique identifier used for the unit_map to recognize the kill
