Ref T261, CAircraftSituationChange improvements

* min/max ground distance, also added in situation list
* use model's vtol/CG info
* improved scenery deviation guessing
* adjusted interpolator scenery deviation handling

tests/blackmisc/testaircraftsituation.h

@@ -64,6 +64,9 @@ namespace BlackMiscTest
 
         //! Set descending altitudes
         static BlackMisc::Aviation::CAircraftSituationList testSetRotateUpPitch(const BlackMisc::Aviation::CAircraftSituationList &situations);
+
+        //! CG
+        static const BlackMisc::PhysicalQuantities::CLength &cg();
     };
 } // namespace