Depend on topkg >= 1.1.0

Track B0_testing.

Fpath.relativize: improve docs and change some suprising results.

Add DEVEL.md (#21).

Fix wrong example in docs (#20).

Use B0_testing.

Renovate README.md

Remove some old source watermarks.

Spdxify.

B0ify.

Update change log.

Switch to contributor based copyrights.

Autumn cleaning.

Require 4.03 and drop result compatibility package.

OCaml 4.12 support: Rearrange types to support the new injectivity annotations in Map.S