remove c#4 features.

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Inspector/ShaderPropertyView.cs

         void DisplayNameField()
         {
             EditorGUI.BeginChangeCheck();
-            property.description = EditorGUILayout.DelayedTextField(property.description);
+            property.displayName = EditorGUILayout.DelayedTextField(property.displayName);
             if (EditorGUI.EndChangeCheck())
                 NotifyNodes();
         }

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Graphs/AbstractMaterialGraph.cs

         public string GetShader(AbstractMaterialNode node, GenerationMode mode, string name, out List<PropertyCollector.TextureInfo> configuredTextures, out PreviewMode previewMode)
         {
             if (node == null)
-                throw new ArgumentNullException(nameof(node));
+                throw new ArgumentNullException("node");
 
             var vertexShader = new ShaderGenerator();
             var surfaceDescriptionFunction = new ShaderGenerator();

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Graphs/AbstractShaderProperty.cs

             }
         }
 
-        public string overrideReferenceName { get; set; } = string.Empty;
+        public string overrideReferenceName { get; set; }
 
         public abstract PropertyType propertyType { get; }
 

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/SubGraph/AbstractSubGraphNode.cs

             }
         }
 
-        public virtual INode outputNode { get; } = null;
+        public virtual INode outputNode
+        {
+            get { return null; }
+        }
 
         public virtual void OnEnable()
         {

MaterialGraphProject/Assets/UnityShaderEditor/Runtime/SubGraph/SubGraphOutputNode.cs

             RemoveSlot(index);
         }
 
-        public override bool allowedInRemapGraph { get; } = false;
+        public override bool allowedInRemapGraph { get { return false; } }
     }
 }