[j.0] XML read/write more compact ()

Device/Detector/OffspecDetector.cpp

Device/Detector/OffspecDetector.h

GUI/Model/Axis/AmplitudeAxisItem.cpp

GUI/Model/Axis/BasicAxisItem.cpp

GUI/Model/Axis/PointwiseAxisItem.cpp

GUI/Model/Beam/BeamDistributionItem.cpp

GUI/Model/Beam/DistributionItems.cpp

GUI/Model/Beam/FootprintItems.cpp

GUI/Model/Beam/GrazingScanItem.cpp

GUI/Model/Beam/SourceItems.cpp

GUI/Model/Data/Data1DItem.cpp

GUI/Model/Data/Data2DItem.cpp

GUI/Model/Data/DataItem.cpp

GUI/Model/Descriptor/AxisProperty.cpp

GUI/Model/Descriptor/DoubleProperty.cpp

GUI/Model/Descriptor/DoubleProperty.h

GUI/Model/Descriptor/VectorProperty.cpp

GUI/Model/Detector/DetectorItem.cpp

GUI/Model/Detector/OffspecDetectorItem.cpp

GUI/Model/Detector/ResolutionFunctionItems.cpp