This should finally allow us to adopt code style lints, as well
as others such as performance linting, and have them enforced by
the Github Actions continuous integration (CI) jobs.
For now, I'm choosing to depend on the 'panolint' gem from
Panorama Education, which is my current workplace, as I'd like
to adopt and stay consistent with the setting used there.
Changes
* Move development and test dependencies from gemspec to Gemfile
* Add dependency on 'panolint' gem
* Add .rubocop.yml
* Fix all existing issues
* Run rubocop in github actions CI
In this PR:
* Temporarily remove all YARD doc config, to be added back
after migrating CI to Github Actions, to simplify config
and dependencies
* Remove all testing and references to < 2.6 Rubies
* Simplify JRuby and TruffleRuby testing to latest stable versions
NOT in this PR:
* Any simplifying code changes that are now possible due to
removing support for EOL Rubies
Closes#58
