Add checked variant

[GeoffSelby]

This PR adds a checked variant per #1255 to allow the styling of checked elements like checkboxes and radios. It is not enabled for anything by default.

[gugahoa]

I merge'd this pull request with a recent fork, and I'm using it in a project. It's working great so far :)

Thanks, @GeoffSelby

Ping @adamwathan

[crnkovic]

What's up with this? Why is this not being merged in?

[adamwathan]

Thanks @GeoffSelby!

[adamwathan]

What's up with this? Why is this not being merged in?

Because pull requests aren't emergencies that I drop everything for and I have lots of other things I need to do as well. Relax mate.

[kungpaogao]

Just wondering, when will this be available for general use? Is there some "beta/nightly" package I can install? Thanks for your hard work!

[adamwathan]

No specific timeline, just whenever we tag the next minor release. Probably next month, have a couple other features I want to get in for v1.5. We don't have a nightly branch or anything but I just pushed up a next tag you can install if you want to play with it now:

npm install tailwindcss@next

[kungpaogao]

Just a heads up, I think being on tailwindcss@next breaks the Tailwind CSS Intellisense for VSCode.