This PR continues #199 by replacing the existing jQuery with Halogen, except for the iframe -- the iframe deserves its own conversation and so I've left it untouched for this pull request. I have avoided changing any features and the application should look and behave the exact same as it currently does.

Well...there's one difference: the old code tried to apply the Ace 'Dawn' theme, but it wasn't working; in this version the dawn theme is present. I can remove the theme altogether if desired, which I believe will default to the TextMate theme.

To review the code I would recommend pulling up the old index.html and old Main.purs files against the new Container.purs Halogen component, as the component wraps in functionality that was previously spread across those two files. To review the functionality I'd just make sure the editor works fine for you. I tested it by putting up the old editor and the new one side-by-side in browser tabs.

I've avoided doing some things that could be changed in the future if we want to clean things up a little:

• I didn't introduce any routing; I instead still rely on the existing query string parsing
• I didn't update to PureScript 0.14 / Halogen 6 (though I'd like to in the near future)
• I only updated one line of CSS (the editor font size), but otherwise left it untouched.
• I matched the Halogen HTML as exactly as possible to the old contents of index.html
• I didn't introduce any new features or update any existing ones

My hope is that this unblocks some of the useful improvements @milesfrain provided a proof-of-concept for (like storing contents in the URL, re-enabling saving gists, and so on); with everything converted to Halogen those could be introduced one-by-one.

Here's a brief demonstration of the before-and-after. First, the current try.purescript.org:

Next, the Halogen version on localhost: