Update beets to 1.4.7

Also updates:
- colorama-0.4.1
- jellyfish-0.6.1
- munkres-1.0.12
- musicbrainzngs-0.6
- mutagen-1.41.1
- pyyaml-3.13
- six-1.12.0
- unidecode-1.0.23

libs/beetsplug/ftintitle.py

@@ -49,29 +49,28 @@ def find_feat_part(artist, albumartist):
     """Attempt to find featured artists in the item's artist fields and
     return the results. Returns None if no featured artist found.
     """
-    feat_part = None
-
     # Look for the album artist in the artist field. If it's not
     # present, give up.
     albumartist_split = artist.split(albumartist, 1)
     if len(albumartist_split) <= 1:
-        return feat_part
+        return None
 
     # If the last element of the split (the right-hand side of the
     # album artist) is nonempty, then it probably contains the
     # featured artist.
-    elif albumartist_split[-1] != '':
+    elif albumartist_split[1] != '':
         # Extract the featured artist from the right-hand side.
-        _, feat_part = split_on_feat(albumartist_split[-1])
+        _, feat_part = split_on_feat(albumartist_split[1])
+        return feat_part
 
     # Otherwise, if there's nothing on the right-hand side, look for a
     # featuring artist on the left-hand side.
     else:
         lhs, rhs = split_on_feat(albumartist_split[0])
         if lhs:
-            feat_part = lhs
+            return lhs
 
-    return feat_part
+    return None
 
 
 class FtInTitlePlugin(plugins.BeetsPlugin):
@@ -90,7 +89,7 @@ class FtInTitlePlugin(plugins.BeetsPlugin):
 
         self._command.parser.add_option(
             u'-d', u'--drop', dest='drop',
-            action='store_true', default=False,
+            action='store_true', default=None,
             help=u'drop featuring from artists and ignore title update')
 
         if self.config['auto']:
@@ -137,7 +136,7 @@ class FtInTitlePlugin(plugins.BeetsPlugin):
         # Only update the title if it does not already contain a featured
         # artist and if we do not drop featuring information.
         if not drop_feat and not contains_feat(item.title):
-            feat_format = self.config['format'].get(unicode)
+            feat_format = self.config['format'].as_str()
             new_format = feat_format.format(feat_part)
             new_title = u"{0} {1}".format(item.title, new_format)
             self._log.info(u'title: {0} -> {1}', item.title, new_title)