This commit adjusts the speech parsing system to allow for an infinite
number of languages to be present in the same message. You can
transition freely between any language you are able to speak simply by
putting it's language key in the middle of the sentence.
Honestly, this was a massive pain in the ass, and there's probably still
broken stuff, even though I've spent around 8 hours testing and refining
this.
Currently, to_chat is literally just a proc that does user << message.
But it'll let us do output modification in the future, especially for
something like Goon's HTML chat.
Big thanks to PJB for his to_chat script, see
https://github.com/d3athrow/vgstation13/pull/6625 for more details.
