[j.tidy2] cleanup suggested by clang-tidy ()

.clang-tidy

App/AppOptions.cpp

Base/Axis/Scale.cpp

Base/Py/PyFmt.cpp

Base/Util/StringUtil.cpp

CMakeLists.txt

Device/Beam/Beam.cpp

Device/IO/ReadWriteTiff.cpp

Device/Mask/Polygon.cpp

Device/Resolution/Convolve.cpp

GUI/Model/Beam/GrazingScanItem.cpp

GUI/Model/Data/Data2DItem.cpp

GUI/Model/Data/DataItem.cpp

GUI/Model/Data/DataItem.h

GUI/Model/Data/MaskResultsPresenter.cpp

GUI/Model/Detector/DetectorItem.cpp

GUI/Model/Device/BackgroundItems.cpp

GUI/Model/Device/DatafileItem.cpp

GUI/Model/Device/DatafileItem.h

GUI/Model/Device/InstrumentItems.cpp