First commit.

Source/OpenNest.Engine/CirclePacking/Item.cs

@@ -0,0 +1,19 @@
+using OpenNest.Geometry;
+
+namespace OpenNest.CirclePacking
+{
+    internal class Item : Circle
+    {
+        public int Id { get; set; }
+
+        public object Clone()
+        {
+            return new Item
+            {
+                Radius = this.Radius,
+                Center = this.Center,
+                Id = this.Id
+            };
+        }
+    }
+}