Make it possible to quit the application

This will call Qt.quit when the Quit application shortcut is pressed (not just
visible=false).

src/main.cpp

@@ -109,6 +109,7 @@ int main(int argc, char *argv[])
     QQmlApplicationEngine engine;
     engine.rootContext()->setContextObject(new KLocalizedContext(&engine));
     KLocalizedString::setApplicationDomain("neochat");
+    QObject::connect(&engine, &QQmlApplicationEngine::quit, &app, &QCoreApplication::quit);
 
     QCommandLineParser parser;
     parser.setApplicationDescription(i18n("Client for the matrix communication protocol"));