some GUI settings not serialized

grep for installIntoGroupBox\( shows that the following sources contain collapsible group boxes for which the collapsed/expanded state is not saved:

• ./GUI/View/Instrument/InstrumentLibraryEditor.cpp
• ./GUI/View/Instrument/OffspecDetectorEditor.cpp
• ./GUI/View/Mask/MaskEditorPropertyPanel.cpp
• ./GUI/View/Project/SimulationView.cpp
• ./GUI/View/Project/ProjectsView.cpp