Passing connection status to airspace monitor.

When the network connection is terminated, airspace monitor
can still recevice pending signals from vatlib. Those have to be ignored.

Otherwise it can happen aircraft (.. etc.) are added again to airspace,
which gives inconsistent results.

src/blackcore/airspace_monitor.h

@@ -99,6 +99,9 @@ namespace BlackCore
         //! Clear the contents
         void clear();
 
+        //! Connection status
+        void setConnected(bool connected);
+
         //! Request to update other clients' data from the network
         void requestDataUpdates();
 
@@ -173,6 +176,7 @@ namespace BlackCore
         CAirspaceWatchdog      m_atcWatchdog;
         CAirspaceWatchdog      m_aircraftWatchdog;
         bool                   m_serverSupportsNameQuery = false; //!< not all servers support name query
+        bool                   m_connected = false;               //!< retrieve data
 
         // TODO FIXME (MS) should be in INetwork
         void sendFsipiCustomPacket(const BlackMisc::Aviation::CCallsign &recipientCallsign) const;