Load TXXX frames that conflict with Picard tags into the ~id3:TXXX namespace
Merge branch 'master' of github.com:musicbrainz/picard into mwiencek-master
Merge branch 'master' of github.com:musicbrainz/picard into mwiencek-master
fix case-sensitivity issues reading TXXX frames
Merge pull request #74 from mwiencek/master

Load TXXX frames that conflict with Picard tags into the ~id3:TXXX namespace
Merge pull request #92 from brainz34/master

Fix: Global plugins are overwriting User-plugins.
Fix a rare TypeError in the metadatabox
Fix: `load_cluster()` does not find existing cluster.

Cluster does not have a meta-data item "artist".

Signed-off-by: brainz34 <brainz34@musicbrainz.org>