* this implementation is used by airspace monitor
* also used by dummy provider (advantage, unit tests test the real provider)
* some functions adjusted
* no longer using the add parts/situations signals
* will use the remote aircraft provider parts directly
Result: all parts/situations are stored only once in memory and in one single place
general idea: by using the plane class, we can set a elevation and then find a better one
* use elevation plane in situation
* adjusted depending classes such as hints, lists
* using setGroundElevationChecked so elevation can be gradually improved