Delegate album_for_id to plugins if no MusicBrainz match is found
Add support for manually entered release ID in Discogs
Determine IDs from MusicBrainz and Discogs URLs
Fix tests for albums from manual ID
Return a list of candidates in hooks._album_for_id
Improve regular expression for Discogs IDs
Fix bug in discogs.album_for_id for ID-Strings that end in a bracket
use album template fields in item templates

This lets you use, for example, the example album bitrate field in path
formats.
Make regex for Discogs ID more specific
Initial support for ALAC encoded audio files

Both AAC and ALAC are normally embedded in an .m4a container. For
this reason I have split the m4a type into aac and alac types.

To distinguish between the two encodings I have taken advantage
of the fact that, in my collection, ALAC don't have a sample_rate
set. I could not find verification if this is always the case
or not. Would bitrate be a more reliable determining factor?
e.g. if bitrate > 320000: type = 'alac'

Signed-off-by: Simon Luijk <simon@simonluijk.com>
Merge pull request #291 from jbaiter/discogs_albumid

Support for manually entered IDs in plugins
fix tests for ID parsing (#291)

The previous tests accessed the network. This refactoring lets us test the ID
parsing in isolation.
#291: simplify plugin interface for album_for_id
#291: restore shortcut for manual ID searches
fix implicit ID search

This was broken because hooks._album_for_id now returns a list. This was
assuming it returned a single value (or None).
#291: plugin hook for track_for_id

For symmetry with album candidates, plugins can now provide item candidates by
ID.
#291: changelog and docs
Style change

Signed-off-by: Simon Luijk <simon@simonluijk.com>
Add note about current approach of detecting aac vs alac

Signed-off-by: Simon Luijk <simon@simonluijk.com>
Fix Python 2.6 compatibility