Set a unique url for each word

[mmai]

This updates the url with a unique hash so we can share words with links like this : https://mmai.github.io/wordlem/#fr-FR/6/AMd

I think this is an interesting feature, but I had to make changes in a lot of places, and I am still discovering elm, so I won't be disapointed if you don't merge this pull request :)

[n1k0]

Thanks!

I didn't look at the code just yet but trying the feature using the demo link you provided, I'm getting this:

Also, on your version, closing the initial Help modal isn't persisted anymore in localStorage, so it shows up every time users refresh the page.

[mmai]

Ah yes, sorry. It should be fixed in the last commit