Add IRCv3 tag support to parseMessage

[MzHub]

http://ircv3.net/specs/core/message-tags-3.2.html

Old syntax:

<message>  ::= [':' <prefix> <SPACE> ] <command> <params> <crlf>

New syntax:

<message>  ::= ['@' <tags> <SPACE>] [':' <prefix> <SPACE> ] <command> <params> <crlf>

where

<tags>          ::= <tag> [';' <tag>]*
<tag>           ::= <key> ['=' <escaped value>]
<key>           ::= [ <vendor> '/' ] <sequence of letters, digits, hyphens (`-`)>
<escaped value> ::= <sequence of any characters except NUL, CR, LF, semicolon (`;`) and SPACE>
<vendor>        ::= <host>

[MzHub]

Apparently there is irc-message in npm too, which supports IRCv3.

[jirwin]

My plan is to use irc-message to parse messages.