Add cross-section convert strategies

StructureHelperCommon/Models/Calculators/IHasCalculators.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperCommon.Models.Calculators
+{
+    public interface IHasCalculators
+    {
+        List<ICalculator> Calculators { get; }
+    }
+}