[xswiftbus] Replace QtDBus with a libevent driven C++ wrapper on top of libdbus

QtDBus was the main component of xswiftbus' Qt dependency. This is the
first preparation step to get xswiftbus Qt free.
The new implementation is based on the low level libdbus library, which
was also in use by QtDBus itself. But instead of QtDBus, we use now a thin
C++ wrapper. To keep DBus handling async, libevent is used to monitor
timeouts and fds.

src/xswiftbus/plugin.h

@@ -20,14 +20,12 @@
 #ifndef NOMINMAX
 #define NOMINMAX
 #endif
+#include "dbusconnection.h"
 #include "menus.h"
-
-#pragma push_macro("interface")
-#undef interface
-#include "blackmisc/dbusserver.h"
-#pragma pop_macro("interface")
-
+#include <QObject>
 #include <QVector>
+#include <memory>
+#include <thread>
 
 namespace XSwiftBus
 {
@@ -46,6 +44,9 @@ namespace XSwiftBus
         //! Constructor
         CPlugin();
 
+        //! Destructor
+        ~CPlugin();
+
         //! Called by XPluginReceiveMessage when the model is changed
         void onAircraftModelChanged();
 
@@ -53,7 +54,7 @@ namespace XSwiftBus
         void onAircraftRepositioned();
 
     private:
-        BlackMisc::CDBusServer *m_server = nullptr;
+        std::unique_ptr<CDBusConnection> m_dbusConnection;
         CService *m_service = nullptr;
         CTraffic *m_traffic = nullptr;
         CWeather *m_weather = nullptr;
@@ -61,8 +62,12 @@ namespace XSwiftBus
         CMenuItem m_startServerMenuItem;
         CMenuItem m_toggleMessageWindowMenuItem;
 
-        void startServer(const QString &address);
-        void tryStartServer(const QString &address);
+        std::thread m_dbusThread;
+        bool m_shouldStop = false;
+
+        void startServer(CDBusConnection::BusType bus);
+
+        static float flightLoopCallback(float, float, int, void *refcon);
     };
 }