Fix parsing of non-latin nicks

[ypeskov]

Hi,

I found an issue when some event are occurring with a user whose nick consists from non Latin characters, it cannot be parsed and as a result it is undefined in such event like "join".

Here is a possible solution

[Throne3d]

I realize this PR has been open for a long time, but just in case anyone stumbles across it and wants support for a wider variety of nicknames, my long-time fork of this repo (irc-upd on npm) has a more comprehensive regex here to parse usernames, as well as some quick tests for the usernames 견본, x/y, and ?nick. It might be worth considering!