read fcts return Datafield instead of pointer

Device/IO/IOFactory.cpp

Device/IO/IOFactory.h

Device/IO/ReadReflectometry.cpp

Device/IO/ReadReflectometry.h

Device/IO/ReadRefsans.cpp

Device/IO/ReadRefsans.h

Device/IO/ReadWrite2DTable.cpp

Device/IO/ReadWrite2DTable.h

Device/IO/ReadWriteINT.cpp

Device/IO/ReadWriteINT.h

Device/IO/ReadWriteNicos.cpp

Device/IO/ReadWriteNicos.h

Device/IO/ReadWriteTiff.cpp

Device/IO/ReadWriteTiff.h

GUI/Model/Axis/PointwiseAxisItem.cpp

GUI/Model/Data/DataItem.cpp

GUI/View/Data/DatafilesSelector.cpp

Tests/Functional/Consistence/CompareTwoReferences.cpp

Tests/Suite/Persist/Check.cpp

Tests/Suite/Py/Check.cpp