Multicont version 1.0.0~rc.1

This is release candidate 1 (and initial release) of the multicont library for OCaml.

This release is compatible with the OCaml 5.0 trunk @ 7f7c0f5 and x64 architectures.

Full Changelog: https://github.com/dhil/ocaml-multicont/commits/v1.0.0-rc.1