Ref T241, further improved interpolation logging

* all interpolation positions can  be logged (3 for spline, 2 for linear)
* interpolated (log) time, setting to real time (i.e. unadjusted time)
* only set logger values with logger attached

src/blackmisc/simulation/interpolator.h

@@ -79,6 +79,9 @@ namespace BlackMisc
             //! \remark parts logging has a \c bool \c log flag
             void attachLogger(CInterpolationLogger *logger) { m_logger = logger; }
 
+            //! Is logger attached
+            bool hasAttachedLogger() const { return m_logger; }
+
             //! Get an interpolator info string (for debug info)
             QString getInterpolatorInfo() const;