Maintenance release to support recent build environments. There are no changes to the interpreter implementation.
- Use GitHub Actions instead of Travis CI
- Add OCaml 4.08 to 4.14 to test matrix
- Update outdated documentation
- Upgrade OPAM version from 1.2 to 2.0
- Upgrade dune from 1.2 to 2.0 or later
- Upgrade base image for Docker images