Add a unicode example.

We're spoiled in D by lovely native, mostly-transparent unicode support.  Output with a C library has a little extra baggage, so I whipped up this example for completeness' sake.

Note: Because there's no standard unicode locale, this depends on the
user's locale.  Consequently, this may not work for all users (likely
people who don't have other unicode working correctly, either).
Moreover, I cannot guarantee adequate glyph coverage for the charaters
used; the current example string is mixed first-level Japanese and ASCII.