This is a refactor of the plugin developed by `imenem`.
- Pass `artist`, `album` and `va_likely` to `candidates()` so that
plugins don't have to work this out from `items` all over again.
- Pass `artist` and `title` to `item_candidates()`.
- Silence spurious `urllib3` info log lines.
- Use a proper "beets" user agent with `discogs_client`.
- Remove `abstract_search` plugin. It seems unnecessary. How many
music databases are there? How many will beets support? How much
common code might there be between them? We can add some abstraction
if or when more databases are supported.
- Derive more AlbumInfo and TrackInfo properties from discogs Release
objects, especially album ID so that beets doesn't just use the first
release and think all subsequent releases are duplicates.
- Add basic documentation, doc strings and code comments.
- Sanitise search query. Remove non-word characters and medium info that
might filter out good search results.
- Use artist `join` strings from discogs Release object when an album
or track has multiple artists.
- Don't rely on discogs track position, which is unreliable. But tracks
are in order, so we can recalculate medium and medium_index as long as
we can extract a consistent medium across tracks from the position.
- Add "various" as a known signal to indicate various artists.
- Prevent `chroma` plugin from returning a a huge track distance for any
track that is missing an ID (e.g. all discog tracks).
- `TrackInfo.index` should be the release index (calculated by beets),
not the medium index (derived from discogs track position).
- Add `AlbumInfo.data_source`. It's "Unknown" by default which is shown
in red when displaying a suggested or selected match. The built in
auto tagger sets it to "MusicBrainz" which is shown in green. Anything
else (e.g. "Discogs") is shown in yellow.
- Remove double spaces from album titles (bad data from Discogs).
I've removed the -p option. The command now always shows plugin-provided
template fields if any are available. We also avoid printing out blank lines
for plugins that don't provide fields.
The major functional change here is how files move around when in keep_new
mode. Now, files are first moved to the destination directory and then
copied/transcoded back into the library.
This avoids problems where naming conflicts could occur when transcoding from
MP3 to MP3 (and thus not changing the filename).
