Fix two issues

Previously special characters in nicks (i.e. `|`) would be treated specially. For example, a setting of `|CoolDude|` would result in everything being nohilighted (because a blank regex alternative matches anything). Use quotemeta on each nick to escape special characters.

I also added `<.?` `>` around the regex so that it won't nohilight just because the nick was in the same line (f.e. `<OtherGuy> Hey zonidjan, isn't |CoolDude| so cool?` should hilight me).