from http://bugs.musicbrainz.org/ticket/1480
'Naming' page has the 'Default' buttons for each of naming specification, so maybe there should be a way to restore other default settings as well. Either a general 'Default' which would restore all, or one for each page.
Merged in https://github.com/metabrainz/picard/commit/d74c244eaf8f026ce567230faf2e11645983210f