Fixed bin id increment twice.

CutList/Forms/ResultsForm.cs

@@ -63,9 +63,8 @@ namespace CutList.Forms
 
             foreach (var bin in Bins)
             {
-                var idString = id++.ToString();
-                var binDescription = $"{idString}. {bin.ToString()}";
-                writer.WriteLine(id++.ToString() + ". " + bin.ToString());
+                var binDescription = $"{id++}. {bin}";
+                writer.WriteLine(binDescription);
 
                 var groups = bin.Items.GroupBy(i => $"{i.Name} {i.Length}");