[j.cleanup] further cleanup in mask context ()

GUI/Model/Data/ProjectionItems.cpp

GUI/Model/Detector/DetectorItem.cpp

GUI/Model/Detector/DetectorItem.h

GUI/Model/Device/InstrumentItems.cpp

GUI/Model/Device/InstrumentItems.h

GUI/Model/Device/RealItem.cpp

GUI/Model/Mask/MaskContainerItem.cpp

GUI/Model/Mask/MaskContainerItem.h

GUI/Model/Mask/MaskContainerModel.cpp

GUI/Model/Mask/MaskContainerModel.h

GUI/View/Import/RealDataMaskWidget.cpp

GUI/View/Mask/MaskEditorActions.h

GUI/View/Mask/MaskEditorCanvas.cpp

GUI/View/Mask/MaskEditorCanvas.h

GUI/View/Mask/MaskEditorFlags.h

GUI/View/Mask/MaskEditorPropertyPanel.h

GUI/View/Mask/MaskEditorToolbar.h

GUI/View/Mask/MaskGraphicsScene.cpp

GUI/View/Mask/MaskGraphicsScene.h

GUI/View/Mask/MaskGraphicsView.h