Add a option to hide peoples international username

[jeffboys123]

FFZ just recently added the option to hide peoples international usernames or hide usernames so only one of them will show instead of having the username in brackets. I think this would be a good feature for most people, as I found out some people I talk to find it very annoying,

[Mm2PL]

This functionality already exists in Chatterino's code. However it does not have any user interface attached to it. If you want to access it you will have to edit config files by hand.