Add radius property to polygon class

[Awkor]

These assignments are now redundant, but I didn't want to delete them because I imagine the comments above them are used to generate the documentation.

I've included a correction regarding the cloning behavior too, let me know if you want that as a separate pull request.

In my previous pull request, I included the documentation changes, should I do the same for this one?

[jonobr1]

Awesome, thanks! This looks good. I believe you can delete the code, but leave the comments so that the documentation is still generated.

Feel free to regenerate the documentation and I'll merge this in.

[Awkor]

Done.

[jonobr1]

Awesome, thank you!