Several documentation callbacks (doc/0 and mod_doc/0) are implemented
and `ejabberdctl man` command is added to generate a man page. Note
that the command requires a2x to be installed (which is a part of
asciidoc package).
When module's options were updated (e.g. by reloading ejabberd.yml)
and, later, the module's process crashed, gen_mod supervisor
restarts the process with outdated options. This is now fixed.