v6.6.0-rc.1

• Includes PRs #24 and #25 by @pturchik.
• Updates dependencies, and bumps supported node version up to >=12.x in package.json.

The changes are not supposed to break anything, but just in case I'll bump the minor release version, and also keep it RC until I have a chance to verify it in my realworld projects. Also pending README update for the new option introduced by #25 .