title: Can I use QApplication AND QCoreApplication?
body: <p>I have a console application using QCoreApplication in Qt5. This application has different functions like "printABC" or "printSUV". The output will appear in the terminal. 
  Now I want to make a Gui, where I can push the buttons "printABC" or "printSUV" and the output will appear in the terminal too, so that it is 'easier' to use the application. 
  In Qt5, I can make a console application using QCoreApplication, which I have already done. 
  So my question is how can I add a QApplication which runs along the way? 
  In the docs, it is recommended to create a QApplication/QCoreApplication in the main function, so how can I create both? </p>