feat(layout): add LayoutPolar

[dustypomerleau]

Happy for any feedback/advice while I work on this. Eventually closes #352.

[andrei-ng]

Looks good so far.
If you could add an example in examples/, then I can expand the mdBook such that it is also included in the book.

[dustypomerleau]

Ok, I finally have green tests using --features=chromedriver,webdriver_download, so I think I'm happy for a review when you have time.

I noticed while adding a layout to the ScatterPolar example that it's the only one without an ANCHOR comment tag—not sure if that's intentional or not.

[andrei-ng]

Ok, I finally have green tests using --features=chromedriver,webdriver_download, so I think I'm happy for a review when you have time.

I noticed while adding a layout to the ScatterPolar example that it's the only one without an ANCHOR comment tag—not sure if that's intentional or not.

I will review it this weekend. I will check the Anchor. It is needed for inclusion in the book. I need to see if it is an omission or international.

Thank you very much for the PR!

[andrei-ng]

Looks good. Merging it. I will make a new release soon.