Small fixes and util addition

[VincentBeaud]

Quick description

• Fix some documentation inconsistencies
• Make chunk Ids start at 0
• Allow compression with a distance threshold of 0
• Add a v_enumerate(x, verbose) function to make enumerate conditionally verbose (using tqdm). Tell me if you think documentation would be relevant for this function.

Type of change

Check the relevant options.

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Provide data, screenshots, command line to test (if relevant)

Checklist

• [x] My code follows the style guidelines of this project (run autopep8)
• [x] I added relevant citations to scripts, modules and functions docstrings and descriptions
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I moved all functions from the script file (except the argparser and main) to scilpy modules
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 68.00%. Comparing base (48911be) to head (d492dca).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #965 +/- ## ======================================= Coverage 67.99% 68.00% ======================================= Files 397 397 Lines 21396 21396 Branches 3239 3239 ======================================= + Hits 14549 14550 +1 + Misses 5532 5531 -1 Partials 1315 1315 ``` | [Components](https://app.codecov.io/gh/scilus/scilpy/pull/965/components?src=pr&el=components&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=scilus) | Coverage Δ | | |---|---|---| | [Scripts](https://app.codecov.io/gh/scilus/scilpy/pull/965/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=scilus) | `68.98% <ø> (ø)` | | | [Library](https://app.codecov.io/gh/scilus/scilpy/pull/965/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=scilus) | `66.50% <50.00%> (+0.01%)` | :arrow_up: |