Leo's beautifier is now pep8 compatible

[Edward K. Ream]

Leo's beautify command is now pep8 compliant, thanks to PR #3057, which is now in devel. In particular, this command formats arguments correctly in defs and calls.

This PR reformats all files in leo.core and leo.commands! My pre-commit test script also beautifies these files, so the new code is well-tested.

Please report any problems immediately. We have plenty of time before the next release.

Edward

P.S. Leo's beautify command differs from black as follows:

- beautify never changes Leo's sentinel comments.

- beautify never splits or joints lines (with the default settings).

  Black sometimes inserts horrible line breaks.

- beautify never converts single-quote strings to double-quote strings.

  Yes, black does have the --skip-string-normalization command-line option.

- beautify doesn't insert extra blank lines at the end of nodes.

  Technically, this is a pep8 violation, but these extra lines are not Leonine.

EKR