Chain route

This new route type allows to glue multiple routes together under a single route. This allows to address them with a single name. Common use-cases are:

* Connecting a path route with a scheme route (forcing HTTPS)
* Connecting a path route with a wildcard route
* Basically any case where you have "may_terminate = false" on the parent and only a single child

Here is a simple example of how the feature can be used:

```php
array(
    'routes' => array(
        'login' => array(
            'type' => 'literal',
            'options' => array(
                'route'    => '/login',
                'defaults' => array(/* … */)
            ),
            'chain_routes' => array(
                array(
                    'type' => 'scheme',
                    'options' => array(
                        'scheme' => 'https'
                    )
                )
            )
        )
    )
);
```

The chains are processed in FIFO order. In the above example, the 'login' route may also have child_routes, in which case the base route of that branch becomes the combined chain of the literal and the scheme route.

The route and factory is designed that way that it allows other modules to easily add conditions (like HTTPS) on a login route without changing the assembling structure.

This PR is so far feature complete, but yet lacks unit tests.