[PR with tiny fixes] Fix help command for subcommands with an executable handler and only a short help flag. Do not use undefined long help option flag in legacy code. Change initial variable values in test for better error messages.

[aweebit]

Tiny fixes that don't really belong anywhere else.

ChangeLog

Changed

• do not call preSubcommand hooks when displaying help for a subcommand with an executable handler
  • (technically breaking, but hey, are we really going to assume someone relied on this?)
• deviating help flags specified for a subcommand with an executable handler via .helpOption() are now respected by the parent's help command (passed to the subcommand instead of the parent's help flag)

Fixed

• .version() optional parameter type
• subcommands with an executable handler and only a short help flag are now handled correctly by the parent's help command
• stopped using undefined long help option flag in legacy code

[aweebit]

The .version() type fix has to agree with whatever decision about the future of the call with no parameters is made in #1954.

Note for myself

One. Change. Per. PR. Always. (no matter how tiny it is)

[shadowspawn]

Couple of good fixes for the reasonably recent possibility the help option might only have short flag.

Changes noted in separate comments.

[shadowspawn]

New changes have gone from fixing a bug with undefined (easy to approve) to refactoring code (opinionated and time consuming to review).

I want the simple fix please.

[aweebit]

Sorry about the force pushes, there is just already enough clutter in other PRs due to this one, and I don't want to introduce even more.

[aweebit]

Thank you for the patience, I know this PR is a mess.

[abetomo]

+1