Replace jshint and csslint with ESLint and Stylelint

[ArmorDarks]

Thanks for great lib!

I think it is time to move from jshint and csslint to today's de facto standards: ESLint and Stylelint.

[tom-spalding]

+1 for ESLint.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[tom-spalding]

not stale