Adding album artist fix
Fix problems with new discogs_client version
set user agent as Client parameter, remove imports
Catch UnreadableFileError when reading files in a (try_)write context
Catch all errors when loading state file.

A crash during the multi-threaded import process may leave the pickled
state invalid (see #913). We recover from all these errors.
mediafile: Catch IndexError when file has empty list tag

Fixes #913
this should fix UnicodeEncodeError with non-ascii queries
lyrics: Use multiple lyrics search strings.

In particular we use the original artist and title before stripping
*and* and *featuring* suffixes.

Fixes #914.
Seems like something broken in new version of discogs_client
Debug log for unreadable state files (#913)
Merge pull request #910 from andriykohut/master

Fix problems with new discogs_client version
Changelog for #910 (fix #915)
Merge pull request #912 from dreewoo/UnreadableFileError

Catch UnreadableFileError when reading files in a (try_)write context
Changelog/thanks for #912
Show album artist stats

See #855
Stats only count albums in the database

Items might have the `album` field set without belonging to an album in
the beets database. We only count the albums that are represented in
the database.
Refactor model formatting

Remove all formatting related code from models. It now lives in the
`FormattedMapping` class. Only API change is from `model.formatted` to
`model.formatted()`.
Item fields take precedence over Album fields in formatting

For consistency, this is reversed when formatting paths. Fixes #858.
convert: Catch errors when writing tags

Fixes #878.
Refactor modfiy command and tests

Parsing of the modify command line is handled by `modfiy_parse_args()`.
Test use the command line.