feature request: use localstorage to improve UX of the try liquidity editor

[martinpospech]

1. Remember which example was open, currently restarting the browser opens the first example.
2. Save code written by user, and
3. Drop down menu to choose previous session.

[mebsout]

Try-Liquidity is not meant to be a full blown editor right now but this is definitely on our roadmap !
I'll update this issue when we have something new on the interface front.

[mebsout]

FWIW, editor state is now saved in the local storage. There is still no way to edit multiple files at once though.