Update Highlightjs

Updated the highlight.js definition for the current version 8.2.0.
The `language` parameter is expected to be a `function` that **returns** a language object (a mode in this case).
If an object (eg an instance of `IModeBase`) is passed, an exception gets thrown.

```
var lang = languages[name] = language(this);
                             ^
TypeError: object is not a function
    at registerLanguage
```