snake_case variable names

See #132, release log:

• c087a6e by @yegor256: #158 multimetric 2.2.0
• 51cde87 by @evermake: fix typo
• 1fd74e7 by @evermake: update ast metric test
• 6c62c3d by @evermake: improve varcomp metric algor...
• e9a108f by @renovate[bot]: Update peter-evans/create-pull...
• 5f0c2cb by @renovate[bot]: Update yegor256/latexmk-action...
• a4ca5b8 by @renovate[bot]: Update yegor256/latexmk-action...
• 5bfbcd4 by @renovate[bot]: Update yegor256/latexmk-action...
• a762eae by @renovate[bot]: Update yegor256/latexmk-action...
• 79c6fff by @renovate[bot]: Update yegor256/latexmk-action...
• cea4863 by @ocelot335: Added few metrics: AHF, SAHF, ...
• b9aa76d by @yegor256: #145 show PMD error to console
• f063e67 by @yegor256: test fixed
• 07fb9a2 by @yegor256: typo
• 0782c7d by @yegor256: Merge pull request #146 from y...
• 94d0811 by @yegor256: install on mac
• 5244f2b by @renovate[bot]: Update yegor256/latexmk-action...
• 9a43411 by @yegor256: eol
• 95c13fb by @yegor256: float fix for all locales
• 5a8d766 by @yegor256: #145 extra test
• and 43 more...

Released by Rultor 2.0-SNAPSHOT, see build log