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.
This commit allows any mob which can speak to choose one of their known
languages as 'default', which makes anything that they say with no
prefix (EG; say 'lol'), use that language.
This commit also changes the 'galactic common' language to use :9
instead of :0, as :0 does not work due to BYOND.. strangeness.
Implements two new IC-tab verbs and updates the check-known-languages
panel to also integrate with this system.
