New MaterialEditor class

GUI/coregui/Models/MaterialItem.cpp

GUI/coregui/Models/MaterialItem.h

GUI/coregui/Models/MaterialModel.cpp

GUI/coregui/Models/MaterialModel.h

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

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

.../Views/Components/MaterialEditor/MaterialEditorWidget.cpp

...ui/Views/Components/MaterialEditor/MaterialEditorWidget.h

...oregui/Views/Components/SampleDesigner/MaterialProperty.h

...coregui/Views/Components/SampleDesigner/SampleToolBar.cpp

GUI/coregui/Views/SampleView.cpp

GUI/coregui/Views/SampleView.h

GUI/coregui/mainwindow/mainwindow.cpp

GUI/coregui/mainwindow/mainwindow.h