Able to right-click and delete shapes

EduNetworkBuilder/Network.cs

@@ -1139,12 +1139,19 @@ namespace EduNetworkBuilder
             Shapes.Add(what);
         }
 
+        public void RemoveShape(NetShape What)
+        {
+            Shapes.Remove(What);
+        }
+
         public NetShape ShapeAtPoint(Point location)
         {
             foreach(NetShape shape in Shapes)
             {
                 if (shape.CornersAreClickedOn(location))
                     return shape;
+                if (shape.CenterIsClickedOn(location))
+                    return shape;
             }
             return null;
         }