Merge branch 'list-agree' into 'master'
Use agree instead of dec_agree This demonstrates that a list-based agreement could work, and form an OFE. I didn't bother to prove all the functor laws. Man, this reasoning with about the lists is annoying^^. What I don't like about this is that un-injection (`agree_car`) is only non-expansive for valid elements. I want to try using a different equivalence relation, maybe I can find one where this works. Cc @jjourdan @robbertkrebbers See merge request !22