Fix possible memleak in CDatabaseWriter

* CApplication network methods cleanup

src/blackmisc/aviation/airportlist.h

@@ -50,8 +50,9 @@ namespace BlackMisc
             //! Find first station by callsign, if not return given value / default
             CAirport findFirstByIcao(const CAirportIcaoCode &icao, const CAirport &ifNotFound = CAirport()) const;
 
-            //! Reads the airport list from JSON
-            static CAirportList fromDatabaseJson(const QJsonArray& json);
+            //! Reads the airport list from database JSON
+            void convertFromDatabaseJson(const QJsonArray& json);
+
         };
     } //namespace
 } // namespace