segmentio/metalsmith-markdown — pull request #1 by FWeinb (2014-03-10 17:04:37+00:00)
Title: Made it possible to use the plugin like `.use(markdown)`

In the [README](https://github.com/segmentio/metalsmith) of metalsmith you use the markdown plugin without bracket like this:

```js
Metalsmith(__dirname)
.use(markdown);
.build([...])
```

But this isn't implemented right now.

This PR will use `.apply` to delegate the function call correctly.

Basically it is just doing this:
```js
if ( arguments.length === 3){
plugin().apply(null, [].slice.call(arguments));
}
```