Adapt to hitode909-san's format

Commits for #42 and http://iiirc.org/snippets/54

@banyan @shikakun 
This patch breaks backward compatibility:

* before - couldn't star server messages and any nick not highlighted
* after - some types of server messages are able to be starred and nick highlighted. For instance, `16:46 kuroda is now known as kuroda_away` is actually server message but handled as `kuroda`'s message

I think this is ok, how do you think?