Add support for Game 3's his files.

Unlike the deal with CIF TREEs, it's easy to identify how to handle the
file based on its contents, so his_conv takes that route instead of
demanding a game number.

Also, game 3 happens to hold a couple of older-style hises (and I'm sure
those one or two his files in Game 11 I couldn't pipe through ogg are
wav-style too), so a game specifier doesn't really fit anyway.