Escape a # in biboumi.1.md

Little documentation update

Document the new way to send private messages

Document the encryption, and a few documentation issues are fixed

Rewrite the whole IID usage

IRC users and channels are now distinguished by the separator used in the
IID (% or !).

ref #2468

Make the XMPP component port configurable

fix #2541

Little doc fix

Update the documentation

Document the `admin` configuration option

Document the new dummy channel, and how biboumi creates and closes connections

Fix a wrong description of how addressing works in biboumi

Reload the conf on SIGUSR1/2

Build the man page as part of the build process, if ronn is found

Little man page update

Document the shutdown procedure

Convert received modes into roles and affiliations

Document the log_file and log_level configuration options

Document the bare-JID-for-IRC-users feature

Provide the doc in markdown format

The included man page is now generated from this markdown file, using ronn

Add some documentation