Back / forward browser buttons don’t work properly

[sapegin]

Was found by @n1313:

1. Click on "open isolated" button for the first example of the Button component.
2. Click "back" in the browser — see that the "Lick me" example is no longer displayed on the page, and that the "open isolated" button for the first example has the wrong icon.
3. Click "forward" in the browser — the page shifts to the left (??) and nothing happens.

There is also an error in the console:

main.bundle.js:26222 Uncaught TypeError: Cannot read property 'type' of undefined

We may need to introduce some proper routing to fix this kind of issues. I don’t mean React Rooter, but something very simple but isolated, not hardcoded in the index.js.

[sapegin]

Routing is a big issue described in #494 but we can probably fix an error here.