compare the backend's version with the plugin's version

src/PlugIn.h

@@ -41,6 +41,7 @@ namespace aman {
         enum class TagItemElement {
         };
 
+        void validateBackendData();
         aman::Aircraft* generateAircraftMessage(const EuroScopePlugIn::CRadarTarget& target);
         void generateAircraftReportMessage(const EuroScopePlugIn::CRadarTarget& radarTarget, aman::AircraftReport* report);
 
@@ -48,6 +49,9 @@ namespace aman {
         std::shared_ptr<RadarScreen> m_screen;
         std::mutex                   m_updateQueueLock;
         std::list<std::string>       m_updateQueue;
+        bool                         m_compatible;
+        std::mutex                   m_airportsLock;
+        std::vector<std::string>     m_airports;
 
     public:
         /**