logs

USE flags

• cli - Enables the Logs_cli library that provides command line support for controlling Logs.
• fmt - Enables the Logs_fmt reporter.
• lwt - Enables the Logs_lwt library that provides Lwt logging functions.
• ocamlopt - Enable ocamlopt support (ocaml native code compiler) -- Produces faster programs (Warning: you have to disable/enable it at a global scale)
• test - Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)