pv: adjust application source code for Qt6 support Prepare application source code (C++ programming language files) for Qt6 compatibility. Implement alternative code paths where the API has changed compared to Qt5. This unbreaks Mac OSX 12 builds with homebrew. This change is based on work that was submitted by Dominik Sliwa <redacted>.
Use QApplication metadata for persistent storage Since the application metadata is set in application.c, we should use it instead of providing it manually every time we create a QSettings object. As I understand it, subclassing QApplication in application.c is only a workaround for bad Qt behavior. In the event that it is removed, the application metadata should be moved so that persistent storage still works.