fix the WTC message

src/PlugIn.cpp

@@ -223,8 +223,10 @@ aman::Aircraft* PlugIn::generateAircraftMessage(const EuroScopePlugIn::CRadarTar
     if (3 <= callsign.length())
         retval->set_airline(callsign.substr(0, 3));
     retval->set_type(flightPlan.GetFlightPlanData().GetAircraftFPType());
-    retval->set_wtc(std::to_string(flightPlan.GetFlightPlanData().GetAircraftWtc()));
-    /* TODO get recat */
+
+    char wtcMessage[2] = { flightPlan.GetFlightPlanData().GetAircraftWtc(), '\0' };
+    retval->set_wtc(wtcMessage);
+
     retval->set_enginecount(flightPlan.GetFlightPlanData().GetEngineNumber());
 
     switch (flightPlan.GetFlightPlanData().GetEngineType()) {