GetPointCount() is now a property

It was impossible to change the SetPointCount on the circle and rectangle shapes because it is impossible to change the get/set definition of a property when overriding. So this is the best I can do for this. See the following link for more information.

http://stackoverflow.com/questions/82437/why-is-it-impossible-to-override-a-getter-only-property-and-add-a-setter