Use semantic versioning (start with v1) and maintain a changelog

> If your software is being used in production, it should probably already be 1.0.0.
(https://semver.org/spec/v2.0.0.html)

Fast.js seems to already be intended for production and has over 3,000 stars.

### But it has no changelog!! :scream:

If you feel like you're too busy to write a changelog, consider using `semantic-release`, which not only automates releases but generates a changelog in your GitHub releases from your (carefully written) commit messages.

Please go ahead and release version 1.0.0 so that
* `npm` can pull in the latest bug fixes when installing `^1.0.0` etc.
* you will be motivated to write a changelog
* users will be able to find breaking change information quickly