rm obsolete MaterialItemUtils

GUI/Model/From/GUIDomainSampleVisitor.cpp

GUI/Model/Job/JobModelFunctions.cpp

GUI/Model/Material/MaterialItemUtils.cpp

GUI/Model/Material/MaterialItemUtils.h

GUI/Model/Material/MaterialModel.cpp

GUI/Model/Sample/ItemWithMaterial.cpp

GUI/Model/Sample/LayerItem.cpp

GUI/Model/Sample/ParticleItem.cpp

GUI/Model/Sample/SampleModel.cpp

GUI/View/MaterialEditor/MaterialEditorDialog.cpp

GUI/View/Tool/DesignerHelper.cpp

Tests/Unit/GUI/TestMaterialModel.cpp