tor --hash-password prefers an argument, but the man page doesn't say so

**--hash-password**::
    Generates a hashed password for control port access.

Should say that it prefers an argument.

There's also some crazy-weird edgecase behavior going on here, where if you say "tor --hash-password" it will pick "", but if you say "tor --hash-password --hush" it will both stop printing out so much, and use "--hush" as your control password. I think. I'm not sure if that wants to be a separate ticket or what.