Counting distribution

[lyonel2017]

Motivation for this change

Porting the distr library from experimental_real in order to use esum (extracted from #2049).

Depends on #2062.

Checklist

• added corresponding entries in CHANGELOG_UNRELEASED.md

• added corresponding documentation in the headers

Reference: How to document

Reminder to reviewers

• Read this Checklist
• Put a milestone if possible
• Check labels

[affeldt-aist]

Note for later: check how le_esum_fine (and le_pos_esum_fine) are used and decide they are worth keeping

[affeldt-aist]

PR #2062 merged -> need rebasing

[lyonel2017]

PR #2062 merged -> need rebasing

I made a rebase.

[affeldt-aist]

The CI is reporting a couple of errors, e.g.:

File "./theories/probability_theory/counting_distr.v", line 157, characters 0-36:
Error: The LHS of ge_ereal_sup
    (ereal_sup _ <= _)%E
does not match any subterm of the goal

[lyonel2017]

A, I messed up something. I will fix this. If that's okay, I will make a few more changes. I started using this PR in a project, and there are things I don't like and/or that are poorly designed (mostly for dlim).

[affeldt-aist]

No problem (we still have to review #2063 beforehand anyway).

Don't hesitate to make micro PRs, especially if among the issues you spotted there are potential fixes to things that have already been merged in master (I am thinking about this PR #2062 we merged some time ago) because we are likely to make a release the end of the month.