Deprecation

Documentation changes to prepare v2.0
Hmm, I think I was not completely clear in my PR. I didn't try to remove `File`, as I think it's still nice to store the filename in the object itself. I just tried to also be more open to save other things, like just `Text` instances.

This makes me think that we might need a more general way to add "attributes" to a text instance to store, for instance, the filename.