refs #369, changed interpolation to a working (but still too bad performing) version

* using split by callsign everywhere
* helper function to insert_front
* revised linear interpolator
* renamed to remoteAircraft
* renamed to container() in providers (gettters are usually copies)

Issues why changes did so long:
* insert in list is not adding in front, but same as push_back (that was confusing)
* naming of values before/after in interpolator was ambigious
* QMap keeps values sorted by key, not arbitrarily

src/blackmisc/sequence.h

@@ -272,6 +272,12 @@ namespace BlackMisc
          */
         void insert(T &&value) { push_back(std::move(value)); }
 
+        /*!
+         * \brief Insert as first element.
+         * \pre The sequence must be initialized.
+         */
+        void insert_front(const T &value) { insert(begin(), value); }
+
         /*!
          * \brief Synonym for push_back.
          * \pre The sequence must be initialized.