Debugger in a div!

## Features
* The debugger is in a `div` on the right side of the window now!
    * It moves with the window
    * It's pretty
    * **It's written in elm!***
    * Watches are pretty printed using a modified `toString` function
    * It can be hidden but still running
    * Scrub back in time whenever you want
* Removed the `html` debugger
    * We don't need the server code to make a frameset webpage
* Start debugging with:
```html
<script type="text/javascript" src="/debugger.js"></script>
<script type="text/javascript">
var todomvc = Elm.debugFullscreen(Elm.Todo, "todo.elm");
</script>
```
It's two lines that do everything needed to summon the debugging panel

### Notes
* *: There is a native module included in `slider/` that implements the slider. It will not go in the catalogue. I'm not sure if this is the best place for it though. Perhaps it should be a git submodule from a repo that I make? <br/>
In addition, there is a javascript file: `debugger.js` that communicates between the debugging interface and the debugging module.

### Todo
* Bump the version
I feel like these names are quite likely to collide with user files. I think we should do more to obfuscate them, but I think in a future PR that's only about this.