[axisitem1] AxisItem clarifications (preliminaries for #562) ()

GUI/Model/Axis/AxisItems.cpp

GUI/Model/Axis/AxisItems.h

GUI/Model/Axis/PointwiseAxisItem.cpp

GUI/Model/Axis/PointwiseAxisItem.h

GUI/Model/CatDevice/MaskItemCatalog.cpp

GUI/Model/Data/DataItem.cpp

GUI/Model/Data/IntensityDataItem.cpp

GUI/Model/Data/MaskItems.cpp

GUI/Model/Data/MaskItems.h

GUI/Model/Data/MaskUnitsConverter.cpp

GUI/Model/Data/MaskUnitsConverter.h

GUI/Model/Data/ProjectionItems.h

GUI/Model/Data/SpecularDataItem.cpp

GUI/Model/Device/DetectorItem.h

GUI/Model/Device/GrazingScanItem.cpp

GUI/Model/Device/InstrumentItems.cpp

GUI/Model/Device/InstrumentNotifier.cpp

GUI/Model/Device/SourceItems.cpp

GUI/Model/FromCore/ItemizeSimulation.cpp

GUI/View/Common/IntensityDataPropertyWidget.cpp