Clean up GUI

recent-developments: Clean up GUI

The GUI was developed with the idea that it is useful and possible to edit configurations (add/remove/edit items) with the GUI.

The current way of working is that configurations are edited with a configuration-file-editor and the GUI is used as a viewer on data, metadata and calculations results.

Therefore menu options like Insert container/data item etc. are not longer in use and removed from the GUI. This is an ongoing process.