[rot2] merge exec_spanZ into spanZ; add "Item" to some function names in GUI ()

Examples/scatter2d/BiMaterialCylinders.py

Examples/scatter2d/CoreShellNanoparticles2.py

Examples/scatter2d/CustomFormFactor.py

Examples/scatter2d/HexagonalLatticesWithBasis.py

Examples/scatter2d/Interference2DCenteredSquareLattice.py

Examples/scatter2d/Mesocrystal2.py

Examples/scatter2d/Mesocrystal3.py

GUI/Model/FromCore/ItemizeSample.cpp

GUI/Model/Model/ParameterTreeUtils.cpp

GUI/Model/Model/ParameterTreeUtils.h

GUI/Model/Sample/CompoundItem.cpp

GUI/Model/Sample/CompoundItem.h

GUI/Model/Sample/LayerItem.cpp

GUI/Model/Sample/LayerItem.h

GUI/Model/Sample/ParticleLayoutItem.cpp

GUI/Model/Sample/ParticleLayoutItem.h

GUI/Model/Sample/SampleItem.cpp

GUI/Model/Sample/SampleItem.h

GUI/View/SampleDesigner/CompoundForm.cpp

GUI/View/SampleDesigner/LayerForm.cpp