Decode the string to UTF8, always

Decode the string to UTF8, always

Even if you know that the caller is passing you a decoded UTF8 string,
you can and should decode it yourself, because some day a caller isn't
going to decode it first and you're going to wind up in misery trying to
figure out why you're broken.

In this case, it resolves the mystery of why the unit tests failed when
Vandelay seemed to be ticking along fine. As the comment in clean_marc()
mentioned, "assume input is already in UTF8" - but as soon as it isn't,
boom.

Signed-off-by: Dan Scott <dscott@laurentian.ca>