Album art (Part 1 of3)
Automated downloading of album art in up to three steps:
1. If CDDMETHOD is musicbrainz cover is downloaded
from coverartarchive by MBID
2. If method 1 fails download is tried from amazon
by ASIN
3. If 1 and 2 fail or CDDBMETHOD is cddb, album will
be downloaded using glyrc by artist + album title
Thanks to Johannes Gernemann for the patch and thanks
to Richard for further development of the patch.
This partially addresses Issue 33 which will be fully
addressed in Parts 2 & 3 of this series of commits.