User data for cracks were added

StructureHelperLogics/NdmCalculations/Cracking/ILengthBetweenCracksLogic.cs

@@ -9,10 +9,23 @@ using System.Threading.Tasks;
 
 namespace StructureHelperLogics.NdmCalculations.Cracking
 {
+    /// <summary>
+    /// Interface of logic of obtaining of length between cracks
+    /// </summary>
     public interface ILengthBetweenCracksLogic : ILogic
     {
+        /// <summary>
+        /// Full collection of ndm parts of cross-section
+        /// </summary>
         IEnumerable<INdm> NdmCollection { get; set; }
+        /// <summary>
+        /// Strain matrix in cracked state
+        /// </summary>
         IStrainMatrix StrainMatrix { get; set; }
+        /// <summary>
+        /// Returns length between cracks
+        /// </summary>
+        /// <returns>Length betwenn cracks</returns>
         double GetLength();
     }
 }