Allow permalinks in the frame-based interface via the URI fragment

This PR allows for permalinks to specific content in rendered APIs whilst retaining the search pane of the frame-based interface. For example, previously the only way to link directly to a class would be something like:

http://api.symfony.com/2.4/Symfony/Component/Yaml/Yaml.html

...but this excludes the search bar. With this change, the following would become possible:

http://api.symfony.com/2.4/#Symfony/Component/Yaml/Yaml.html

This would link the user to the API docs for the `Yaml` class, and the search pane would still be visible, and functional.