Re: [PATCH] Add: tracktag interface and support for Opus

[Grant Shoshin Shangreaux]

The contents of this patch (with the tests removed for now) have been
pushed to the opus-tags branch of the savannah repository.

Any testing and feedback is welcome. I plan to run through several
scenarios with files on my system over the next few days. So far, so
good. I've tagged a few Opus files on my system and worked out a few
kinks already. I will also try it out with some other formats.

One caveat of tracktag, it doesn't write a genre tag, oddly. Perhaps
because it is inconsistent in metadata formats? I will try to improve
the tag editor so it will not present it as an option if tracktag is the
selected backend.

Another oddity I see is that EMMS info has info-year in most places, but
info-date appears in a few other. is there an actual distinction for
some metadata?