Cleanup aircraft in X-Plane after DBusConnection drops

ref T392

src/xswiftbus/dbusobject.h

@@ -36,9 +36,15 @@ namespace XSwiftBus
         void registerDBusObjectPath(const std::string &interfaceName, const std::string &objectPath);
 
     protected:
+        //! Handler which is called when DBusCconnection is established
+        virtual void dbusConnectedHandler() {}
+
         //! DBus message handler
         virtual DBusHandlerResult dbusMessageHandler(const CDBusMessage &message) = 0;
 
+        //! Handler which is called when DBusConnection disconnected
+        virtual void dbusDisconnectedHandler() {}
+
         //! Send DBus signal
         void sendDBusSignal(const std::string &name);