Refactoring of some SessionItem methods

GUI/coregui/Models/DetectorItems.cpp

GUI/coregui/Models/DomainObjectBuilder.cpp

GUI/coregui/Models/JobModel.cpp

GUI/coregui/Models/MesoCrystalItem.cpp

GUI/coregui/Models/ParameterTreeUtils.cpp

GUI/coregui/Models/ParticleCompositionItem.cpp

GUI/coregui/Models/ParticleCoreShellItem.cpp

GUI/coregui/Models/ParticleDistributionItem.cpp

GUI/coregui/Models/ParticleLayoutItem.cpp

GUI/coregui/Models/SampleValidator.cpp

GUI/coregui/Models/SessionItem.cpp

GUI/coregui/Models/SessionItem.h

GUI/coregui/Models/SessionXML.cpp

GUI/coregui/Models/TransformToDomain.cpp

GUI/coregui/Views/PropertyEditor/ComponentEditor.cpp

GUI/coregui/Views/PropertyEditor/ComponentEditorPrivate.cpp

GUI/coregui/Views/SampleDesigner/SampleViewAligner.cpp

Tests/UnitTests/GUI/TestGroupProperty.h

Tests/UnitTests/GUI/TestParticleDistributionItem.h

Tests/UnitTests/GUI/TestParticleItem.h