Logging infrastructure for OCaml

Logs provides a logging infrastructure for OCaml. Logging is performed
on sources whose reporting level can be set independently. Log message
report is decoupled from logging and is handled by a reporter.

A few optional log reporters are distributed with the base library and
the API easily allows to implement your own.

`Logs` depends only on the `result` compatibility package. The
optional `Logs_fmt` reporter on OCaml formatters depends on [Fmt][fmt].
The optional `Logs_browser` reporter that reports to the web browser
console depends on [js_of_ocaml][jsoo]. The optional `Logs_cli` library
that provides command line support for controlling Logs depends on
[`Cmdliner`][cmdliner]. The optional `Logs_lwt` library that provides Lwt logging
functions depends on [`Lwt`][lwt]

Logs and its reporters are distributed under the ISC license.

[fmt]: http://erratique.ch/software/fmt
[jsoo]: http://ocsigen.org/js_of_ocaml/
[cmdliner]: http://erratique.ch/software/cmdliner
[lwt]: http://ocsigen.org/lwt/
