Context

Expand Lwtreslib with an Option module.

(Part of !1872 (closed))

Waiting for !2422 (merged) to be merged: it removes some uses of TzOption which simplifies this MR.

Manually testing the MR

Automatic testing

Normal CI tests.

Reviewers

@mbouaziz @Saroupille

Edited Jan 27, 2021 by Raphaël Proust