Properly send error response on presence stanzas
Return a stanza error whenever the IRCClient for a given server does not exist
Instead of ignoring the stanza, we send back an error of type
remote-server-not-found each time it's possible.
Also avoid having to do if (!irc) return; everytime.
Support raw IRC messages
Messages received on an IRC server JID are forwarded as raw IRC messages.
Move non-specific adhoc commands into louloulibs
Only keep some biboumi-specific commands into biboumi_adhoc_commands.hpp/cpp
Remove all the libs that are now in louloulibs