Add function material interface and button

StructureHelperLogics/Models/Materials/IFunctionMaterial.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperLogics.Models.Materials
+{
+    internal interface IFunctionMaterial : IHelperMaterial
+    {
+
+    }
+}