Add visibility and regular expression based filtering

[lucatume]

This PR:

• adds support for the --visibility option to control the visibility of the methods to return; e.g. --visibility=public to return public methods only
• add support for the --methodRegex option to filter methods by regular expression; e.g. --methodRegex="/^[^_]/" to exclude any method starting with_`. I've updated the code and the tests but not the documentation, let me know, thanks for your work.

[lucatume]

I've added support for another option: --tableGenerator. This allows changing the output format still using the command (super) powers, the option argument should be a slug mapped to a table generator (currently only default) or a fully-qualified table generator class name. I've created the TableGenerator interface to guide development of table generators.

As an example I'm using it like this:

phpdoc-md generate \
            --visibility=public \
            --methodRegex="/^[^_]/" \
            --tableGenerator=tad\\WPBrowser\\Documentation\\TableGenerator \
            Codeception\Module\WordPress > ${CURDIR}/docs/modules/WordPress.md;

Here's the current tad\WPBrowser\Documentation\TableGenerator code: https://github.com/lucatume/wp-browser/blob/module-docs/src/tad/WPBrowser/Documentation/TableGenerator.php

[lucatume]

Is there something I should/could do to move this forward? Do my changes seem to bring value?

[lucatume]

Thanks @peter279k for your comments and review: I've updated the code as per your comments and should be ready for another look.

[peter279k]

Excluding the coding style, it looks good to me.

Perhaps repo owner, @victorjonsson should organize/define the coding style for this repository.

And let the contributor make the PR easy to do contribution.

[lucatume]

@victorjonsson Hi there, is there anything I should do to have this merged? Are you interested in this PR at all?

[lucatume]

Thanks @victorjonsson