Add ipv6 to windows mdns.
Fix compile errors.
Revert "Add ipv6 to windows mdns."
Extend tag support: performer, grouping

The transaction handling while upgrading the database schema had to be revised.
Furthermore some QSqlQuery statements needed to be finished properly.

Fixes issue 2556
Fix style, hide the new columns by default, and move the new columns to the end of the enum
Blur the colour channels instead of just the alpha channel of playlist
background images.  Fixes issue 3498
Automatic merge of translations from Transifex (https://www.transifex.net/projects/p/clementine/resource/clementineplayer)