Utility libraries to use with [pp]

[pplumbing] defines a set of utility libraries to use with pp. It is compatible with logs and inspired by design choices used by dune for user messages.

These libraries are meant to combine nicely into a small ecosystem of useful helpers to build CLIs in OCaml.

• [Pp_tty] extends pp to build colored documents in the user's terminal using ansi escape codes.

• [Err] is an abstraction to report located errors and warnings to the user.

• [Log] is an interface to logs using [Pp_tty] rather than [Format].

• [Log_cli] contains functions to work with [Err] on the side of end programs (such as a command line tool). It defines command line helpers to configure the [Err] library, while taking care of setting the logs and fmt style rendering.

• [Cmdlang_cmdliner_runner] is a library for running command line programs specified with cmdlang with cmdliner as a backend and making opinionated choices, assuming your dependencies are using [Err].