CHANGES (u.43595d19ce7739d8c65c03043dcd23ef.mirage-clock.4.2.0.doc.CHANGES)

Be able to build & instal the distribution via opam without the expected dune's context (@TheLortex, @dinosaure, #49)

Remove Mirage_clock_lwt module (#48 @hannesm)
Use caml_get_wall_clock instead of unix_gettime to avoid floating point conversion roundtrip (#47 @hannesm)

Use implicit executable dependency for discover.exe into the dune file (#46 @TheLortex)
Fix cross-compilation on Android (#45 @EduardoRFS)

Constrain the clock type t to unit to improve compatability with the webmachine CLOCK interface. All current implementations satisfy this interface so there shouldn't be an issue, but bumping the library major version number to reflect the interface change (#38 @hannesm)
Port library to Dune from jbuilder and use dune-release and the builtin dune.configurator to reduce the build dependency cone (#39 @avsm).
Remove unused variable warnings (#39 @avsm).
Update opam package metadata to 2.0 format (#39 @avsm).
Fixes to the ocamldoc comment headers for odoc compatibility (@avsm)

import V1.MCLOCK and V1.PCLOCK from mirage-types under mirage-clock and mirage-clock-lwt