Adding Monomorphisation procedure to Zipperposition

[nartannt]

Hi,
I have implemented the iterative monomorphisation procedure described here in a fork of Zipperposition, it allows for significant performance gains on polymorphic problems. It seems worthwhile to import it to the main Zipperposition repository.

As it stands, the code has the following issues:

• the formatting is not compatible with the current code of the main repository, I have been unable to replicate that formatting style
• I am unsure that the code quality and style are up to par with that of the main repository
• There are some modifications of the codebase outside the scope of the Monomorphisation.ml file particularly in the eprover.ml file

[c-cube]

sorry I didn't reply sooner. Can you use this format config and ocamlformat 0.27? I do think it's a good idea to use ocamlformat now.

other cleanup to do:

• move to at least 4.14 as lower bound
• make sure CI checks for formatting
• run large sets of benchmarks regularly to detect regressions
• make sure all dependencies are recent
• use ocaml-trace for the tracing part
• use logs for logging
• and, one day, have a proper proof output format that can be checked 🙃

[c-cube]

Giving you write access so you can more easily fix what needs to be fixed :-).