[ENH] Implicit orangecontrib namespace

[markotoplak]

No description provided.

[markotoplak]

Hmm, I have no idea why this fails. tox -e orange-released worked for me locally.

[stuart-cls]

Chasing something else, I remembered this PR and realized I'd forgotten to remove orangecontrib/__init__.py on prototypes.

But when I did so, there was no problem with the relative import (from . import data) (see tests)

I'm getting the same error locally as the runners in this PR though.