refs #863 Each aircraft gets its own interpolator instance,

so each one can cache calculations from one frame to the next.
The recent situations and parts are members of the interpolator.

src/blackmisc/simulation/interpolatorlinear.h

@@ -25,15 +25,13 @@ namespace BlackMisc
     namespace Aviation { class CCallsign; }
     namespace Simulation
     {
-        class IRemoteAircraftProvider;
-
         //! Linear interpolator, calculation inbetween positions
         class BLACKMISC_EXPORT CInterpolatorLinear : public IInterpolator
         {
         public:
             //! Constructor
-            CInterpolatorLinear(BlackMisc::Simulation::IRemoteAircraftProvider *provider, QObject *parent = nullptr) :
-                IInterpolator(provider, "CInterpolatorLinear", parent)
+            CInterpolatorLinear(QObject *parent = nullptr) :
+                IInterpolator("CInterpolatorLinear", parent)
             {}
 
             // public base class signature