refs #187, asyncConnectTo method to avoid freeze when starting GUI/Core

* as discussed in https://dev.vatsim-germany.org/issues/187#change-1183
* using no longer connectTo() but asyncConnectTo() in constructor of simulator context
* changed Interface doxygen comments to copydoc

src/blackcore/context_simulator.h

@@ -62,6 +62,9 @@ namespace BlackCore
         //! \brief Connect to simulator
         virtual bool connectTo() = 0;
 
+        //! \brief Connect to simulator (asynchronous version)
+        virtual void asyncConnectTo() = 0;
+
         //! \brief Disconnect from simulator
         virtual bool disconnectFrom() = 0;
 

src/blackcore/context_simulator_impl.cpp

@@ -24,7 +24,7 @@ namespace BlackCore
         loadSimulatorPlugin(CSimulatorInfo::FSX());
 
         connect(m_updateTimer, &QTimer::timeout, this, &CContextSimulator::updateOwnAircraft);
-        connectTo();
+        asyncConnectTo();
     }
 
     CContextSimulator::~CContextSimulator()
@@ -64,6 +64,13 @@ namespace BlackCore
         return m_simulator->connectTo();
     }
 
+    void CContextSimulator::asyncConnectTo()
+    {
+        if (this->getRuntime()->isSlotLogForSimulatorEnabled()) this->getRuntime()->logSlot(Q_FUNC_INFO);
+        if (!m_simulator || m_canConnectResult.isRunning()) return; // already checking
+        this->m_canConnectResult = QtConcurrent::run(this, &CContextSimulator::connectTo);
+    }
+
     bool CContextSimulator::disconnectFrom()
     {
         if (this->getRuntime()->isSlotLogForSimulatorEnabled()) this->getRuntime()->logSlot(Q_FUNC_INFO);

src/blackcore/context_simulator_impl.h

@@ -15,6 +15,7 @@
 
 #include <QTimer>
 #include <QDir>
+#include <QtConcurrent/QtConcurrent>
 
 namespace BlackCore
 {
@@ -39,13 +40,16 @@ namespace BlackCore
         //! \copydoc IContextSimulator::isConnected()
         virtual bool isConnected() const override;
 
-        //! \brief Can we connect?
+        //! \copydoc IContextSimulator::canConnect
         virtual bool canConnect() override;
 
-        //! \brief Connect to simulator
+        //! \copydoc IContextSimulator::connectTo
         virtual bool connectTo() override;
 
-        //! \brief Disconnect from simulator
+        //! \copydoc IContextSimulator::asyncConnectTo
+        virtual void asyncConnectTo() override;
+
+        //! \copydoc IContextSimulator::disconnectFrom
         virtual bool disconnectFrom() override;
 
         //! \copydoc IContextSimulator::getOwnAircraft()
@@ -88,6 +92,7 @@ namespace BlackCore
         QTimer *m_updateTimer;
         QDir m_pluginsDir;
         QSet<ISimulatorFactory *> m_simulatorFactories;
+        QFuture<bool> m_canConnectResult;
     };
 
 } // namespace BlackCore

src/blackcore/context_simulator_proxy.cpp

@@ -48,6 +48,11 @@ namespace BlackCore
         return m_dBusInterface->callDBusRet<bool>(QLatin1Literal("connectTo"));
     }
 
+    void CContextSimulatorProxy::asyncConnectTo()
+    {
+        m_dBusInterface->callDBus(QLatin1Literal("asyncConnectTo"));
+    }
+
     bool CContextSimulatorProxy::disconnectFrom()
     {
         return m_dBusInterface->callDBusRet<bool>(QLatin1Literal("disconnectFrom"));

src/blackcore/context_simulator_proxy.h

@@ -42,13 +42,16 @@ namespace BlackCore
         //! \copydoc IContextSimulator::isConnected()
         virtual bool isConnected() const override;
 
-        //! \brief Can we connect?
+        //! \copydoc IContextSimulator::canConnect
         virtual bool canConnect() override;
 
-        //! \brief Connect to simulator
+        //! \copydoc IContextSimulator::connectTo
         virtual bool connectTo() override;
 
-        //! \brief Disconnect from simulator
+        //! \copydoc IContextSimulator::asyncConnectTo
+        virtual void asyncConnectTo() override;
+
+        //! \copydoc IContextSimulator::disconnectFrom
         virtual bool disconnectFrom() override;
 
         //! \copydoc IContextSimulator::getOwnAircraft()