hg-core: add basic config module
The config module exposes a `Config` struct, unused for now.
It only reads the config file local to the repository, but handles all valid
patterns and includes/unsets.
It is structured in layers instead of erasing by reverse order of precedence,
allowing us to transparently know more about the config for debugging purposes,
and potentially other things I haven't thought about yet.
This change also introduces `format_bytes!` to `hg-core`.
Differential Revision: https://phab.mercurial-scm.org/D9408
// config.rs
//
// Copyright 2020
// Valentin Gatien-Baron,
// Raphaël Gomès <rgomes@octobus.net>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.
//! Mercurial config parsing and interfaces.
mod config;
mod layer;
pub use config::Config;