message: Set AA_EnableHighDpiScaling attribute early
  Qt docs: This attribute must be set before QGuiApplication is
  constructed.
diff: @@ -436,16 +436,17 @@ int GuiMain(int argc, char* argv[])
  Q_INIT_RESOURCE(bitcoin);
  Q_INIT_RESOURCE(bitcoin_locale);
  - BitcoinApplication app(*node, argc, argv);
  // Generate high-dpi pixmaps
  QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
  #if QT_VERSION >= 0x050600
  - QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
  + QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
  #endif
  #ifdef Q_OS_MAC
  QApplication::setAttribute(Qt::AA_DontShowIconsInMenus);
  #endif
  + BitcoinApplication app(*node, argc, argv);
  +
  // Register meta types used for QMetaObject::invokeMethod
  qRegisterMetaType< bool* >();
  // Need to pass name here as CAmount is a typedef (see http://qt-project.org/doc/qt-5/qmetatype.html#qRegisterMetaType)
  