Refactoring in PropertyAttribute.

GUI/coregui/Models/GroupProperty.cpp

GUI/coregui/Models/GroupProperty.h

GUI/coregui/Models/ItemFactory.cpp

GUI/coregui/Models/MultiLayerItem.cpp

GUI/coregui/Models/ParaCrystalItems.cpp

GUI/coregui/Models/ParameterizedGraphicsItem.cpp

GUI/coregui/Models/ParameterizedItem.cpp

GUI/coregui/Models/ParameterizedItem.h

GUI/coregui/Models/ParticleCoreShellItem.cpp

GUI/coregui/Models/PropertyAttribute.h

GUI/coregui/Models/item_constants.h

.../Views/Components/SampleDesigner/SamplePropertyEditor.cpp

GUI/coregui/mainwindow/mainwindow.cpp