Use new tagging stuff to read and write flac metadata. Only handles vorbiscomment...

Use new tagging stuff to read and write flac metadata. Only handles vorbiscomment tags, and not (older) id3v2 tags.

Original commit message from CVS:
Use new tagging stuff to read and write flac metadata. Only handles vorbiscomment tags, and not (older) id3v2 tags.