Merge: nitdoc: prepare the migration of nitdoc component to new phases

Only internal modification, no diff with the generated HTML of the previous version.

If you don't trust me (I you shouldn't), the demos will be [there](http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/stdlib/index.html) and [there](http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/nitc/index.html) in a few minutes.

> Brace yourself, next PR on that subject will be big.

Pull-Request: #1293
Reviewed-by: Jean Privat <jean@pryen.org>