Major port Qt4 to Qt6

- Updated header inclusions from QtGui to QtWidgets for consistency and compatibility with Qt 5 and later.
- Replaced deprecated QApplication::desktop() with QApplication::primaryScreen() for obtaining screen DPI.
- Modified MyOutputHandler to use QMessageLogContext and QString for improved logging.
- Changed QMatrix to QTransform for image rotation in ImageCutout class.
- Updated various debug statements to use toLocal8Bit() instead of toAscii() for better string handling.
- Refactored several classes to use QElapsedTimer instead of QTime for performance measurement.
- Ensured all operator overloads in Section and Tag classes are marked as const for better const-correctness.

ClippingStation/globalfunctions.h

@@ -107,6 +107,6 @@ int download(CURL* curlhandle, const char * remoepath, const char * localpath,
              long timeout, long tries, char * strerror);
 
 
-void MyOutputHandler(QtMsgType type, const char *msg);
+void MyOutputHandler(QtMsgType type, const QMessageLogContext &context, const QString &msg);
 
 #endif // GLOBALFUNCTIONS_H