Ontology._get_parsers behaviour to look for parsers
through a setuptools entrypoint instead of mere subclasses.
(The original entry is located in /home/docs/checkouts/readthedocs.org/user_builds/pronto/checkouts/latest/pronto/ontology.py:docstring of pronto.Ontology._get_parsers, line 3.)
- Add a warning for unknown relationship (the goal being to instantiate every known ontology relationship and even allow instatiation of file-defined relationships).
(The original entry is located in /home/docs/checkouts/readthedocs.org/user_builds/pronto/checkouts/latest/pronto/relationship.py:docstring of pronto.Relationship.__new__, line 13.)