Support "Cut" command

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/MaterialGraphEditWindow.cs

             if (e.type == EventType.ValidateCommand && (
                 e.commandName == "Copy" && presenter.canCopy
                 || e.commandName == "Paste" && presenter.canPaste
-                || e.commandName == "Duplicate" && presenter.canDuplicate))
+                || e.commandName == "Duplicate" && presenter.canDuplicate
+                || e.commandName == "Cut" && presenter.canCut))
             {
                 e.Use();
             }
                     presenter.Paste();
                 if (e.commandName == "Duplicate")
                     presenter.Duplicate();
+                if (e.commandName == "Cut")
+                    presenter.Cut();
             }
         }
 

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Presenters/MaterialGraphPresenter.cs

             EditorGUIUtility.systemCopyBuffer = JsonUtility.ToJson(graph, true);
         }
 
+        public bool canCut
+        {
+            get { return canCopy; }
+        }
+
+        public void Cut()
+        {
+            Copy();
+            RemoveElements(elements.OfType<MaterialNodePresenter>().Where(e => e.selected), elements.OfType<GraphEdgePresenter>().Where(e => e.selected));
+        }
+
         public bool canPaste
         {
             get { return DeserializeCopyBuffer(EditorGUIUtility.systemCopyBuffer) != null; }

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Views/MaterialGraphView.cs

         // TODO JOCE Remove the "new" here. Use the base class' impl
         new EventPropagation DeleteSelection()
         {
-            var nodalViewData = GetPresenter<MaterialGraphPresenter>();
-            if (nodalViewData == null)
+            var presenter = GetPresenter<MaterialGraphPresenter>();
+            if (presenter == null)
-            nodalViewData.RemoveElements(
+            presenter.RemoveElements(
                 selection.OfType<MaterialNodeView>().Select(x => x.GetPresenter<MaterialNodePresenter>()),
                 selection.OfType<Edge>().Select(x => x.GetPresenter<GraphEdgePresenter>())
                 );