refs #270 don't call CRuntime::gracefulShutdown from a different thread;

connect it to the QCoreApplication::aboutToQuit signal instead

samples/blackcore/tool.cpp

@@ -154,7 +154,6 @@ namespace BlackMiscTest
                 else if (line.startsWith("all")) runtime->slotLog(enable);
             }
         }
-        runtime->gracefulShutdown();
         QCoreApplication::quit();
     }
 } // namespace

src/blackcore/context_runtime.cpp

@@ -305,6 +305,8 @@ namespace BlackCore
         BlackSim::registerMetadata();
         BlackCore::registerMetadata();
 
+        this->connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit, this, &CRuntime::gracefulShutdown);
+
         // upfront reading of settings, as DBus server already relies on settings
         CContextSettings *settings = nullptr;
         QString dbusAddress;

src/blackcore/context_runtime.h

@@ -139,7 +139,7 @@ namespace BlackCore
         //! Slot logging for bool value from a specific context
         void logSlot(LogContext ctx, const char *func, bool boolValue) const;
 
-        //! shutdown
+        //! Clean up (will be connected to signal QCoreApplication::aboutToQuit)
         void gracefulShutdown();
 
         // ------- Context as interface, normal way to access a context