Custom message formatting for jailed players

[S-S-X]

First of all fixes #90 where formatting was dropped completely.

But wont restore generic formatting but instead adds jail channel specific formatting for jailed players, players who are not jailed will still utilize generic / global formatting.

Makes format_string function public, this was local before but it seems it could be useful to allow special formatting through plugins. Even for this one case I think it is better to just expose that function to public, it allows handling beerchat format strings without having to know about internals.

Then also this is not only way, generic formatting could still be used. I just think it is worse for jail and this gave good opportunity to change that.

Beg to differ? Well, there's text box where beggars can go beg down there ⬇️

[S-S-X]

Also

• fix message duplication for jailed players
• add basic chat tests for jail message duplication
• move logging to event-logging.lua
• "fix" some beerchat.send_message issues