Don't cut off last character of original template

With a simple jade template, `layout.jade`:

```
doctype 5
html
  body
```

And a simple render:

```
exports.index = (req, res) ->
  res.render 'layout'
```

The html that results after mixing in the EDT markup cuts off the closing bracket of the starting body tag, looking in part like this:

```
<!DOCTYPE html><html><body<style type="text/css">/* SHOW/HIDE buttons */
#EDT-show {
...
```