Crack Calculator was added

StructureHelperCommon/Models/Calculators/IResult.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperCommon.Models.Calculators
+{
+    public interface IResult
+    {
+        /// <summary>
+        /// True if result of calculation is valid
+        /// </summary>
+        bool IsValid { get; set; }
+        string Description { get; set; }
+    }
+}