Add import of polygon from dxf

StructureHelperCommon/Infrastructures/Exceptions/ErrorString.cs

@@ -29,5 +29,7 @@
         public static string CalculationError => "#0019: Error of calculation";
         public static string SourceObject => "#0020: Source object";
         public static string TargetObject => "#0021: Target object";
+        public static string FileDoesNotExsist => "#0022: File does not exist";
+        public static string FileCantBeOpened => "#0023: File can not be opened";
     }
 }

StructureHelperCommon/Infrastructures/Interfaces/IObjectConvertStrategy.cs

@@ -6,8 +6,18 @@ using System.Threading.Tasks;
 
 namespace StructureHelperCommon.Infrastructures.Interfaces
 {
+    /// <summary>
+    /// Implements logic for convert from one object to another one
+    /// </summary>
+    /// <typeparam name="T">Type of target object</typeparam>
+    /// <typeparam name="V">Type of source object</typeparam>
     public interface IObjectConvertStrategy<T, V>
     {
+        /// <summary>
+        /// Converts sourve object to another one
+        /// </summary>
+        /// <param name="source">Source object</param>
+        /// <returns>Target object</returns>
         T Convert(V source);
     }
 }