Allow combining or replacing measurement points from files

**This issue is a feature request**

Measurement points should be combined or replaced depending on user choice

* **What is the current behaviour?**

The old measurement points are always replaced

* **What is the expected behaviour?**

When adding measurement points from a file, a message box should ask if the points should be combined or replaced similar to the 3D model. If the user selects, **combine** the new points in the file should be combined with the ones in the measurement points list and selecting **replace** will keep the current behaviour are replace the old points with new points from the file. The message box should show only if points have been added if no points have been added simply add them as normal