Cleanup from old MaterialBrowser remnants. New MaterialEditor is connected.

GUI/coregui/Models/LayerItem.cpp

GUI/coregui/Models/MaterialModel.cpp

GUI/coregui/Models/MaterialModel.h

GUI/coregui/Models/ParameterizedItem.cpp

GUI/coregui/Models/SessionModel.cpp

...oregui/Views/Components/MaterialEditor/MaterialEditor.cpp

GUI/coregui/Views/Components/MaterialEditor/MaterialEditor.h

...coregui/Views/Components/MaterialEditor/MaterialUtils.cpp

...Views/Components/SampleDesigner/DesignerWidgetFactory.cpp

...oregui/Views/Components/SampleDesigner/FormFactorView.cpp

GUI/coregui/Views/Components/SampleDesigner/FormFactorView.h

...regui/Views/Components/SampleDesigner/MaterialBrowser.cpp

...coregui/Views/Components/SampleDesigner/MaterialBrowser.h

.../Views/Components/SampleDesigner/MaterialBrowserModel.cpp

...ui/Views/Components/SampleDesigner/MaterialBrowserModel.h

...i/Views/Components/SampleDesigner/MaterialBrowserView.cpp

...gui/Views/Components/SampleDesigner/MaterialBrowserView.h

...ui/Views/Components/SampleDesigner/MaterialEditorView.cpp

...egui/Views/Components/SampleDesigner/MaterialEditorView.h

GUI/coregui/Views/Components/SampleDesigner/MaterialView.cpp