Plugin perspective / brainstorm

What would be awesome would be, using Psysh, to be able to register extensions, so that it may register custom commands (without going through a PR here), outputs, presenters, ... or whatever else.

Just launching the discussion here, so that we may maybe get some ideas. I was thinking of something like how Twig does it (Or Symfony2 and its bundles, as this is more complete but also more tedious)

Any thoughts ?