implement regexp pattern for handling IRC events

:open_mouth:

Everything important is in the `match` array.

match[0] = Entire IRC command (ex: `:verne.freenode.net PONG verne.freenode.net :TIMEOUTCHECK`)
match[1] = Hostname (ex: `verne.freenode.net`, `vevix@127.0.0.1`)
match[2] = IRC command (ex: `PONG`, `PRIVMSG`, `NICK`)
match[3] = Destination (user, channel etc.) (ex: `verne.freenode.net`, `vevix`, `#channel`)
match[4] = Message (`TIMEOUTCHECK`, `Hello, World!`)

Also, gofmt decided to do some cleanup :shipit: