Cleaned the code related to the playground.

I cleaned the code related to the the website's playground, before implementing new features. It was only formatting, no refactoring.
Implemented routing for the playground.

Now the playground page of the website handles routing to navigate through samples, which means that each sample has its own URL, and loading this URL will show the sample. History is supported as well.

flatiron/director (https://github.com/flatiron/director) is used to handle this routing.