scrobble with brainz trackid, not album id

scanner/scanner.go

@@ -336,6 +336,7 @@ func (s *Scanner) handleTrack(it *item) error {
 	track.TagTrackArtist = trTags.Artist()
 	track.TagTrackNumber = trTags.TrackNumber()
 	track.TagDiscNumber = trTags.DiscNumber()
+	track.TagBrainzID = trTags.BrainzID()
 	track.Length = trTags.Length()   // these two should be calculated
 	track.Bitrate = trTags.Bitrate() // ...from the file instead of tags
 	//

scanner/tags/tags.go

@@ -34,6 +34,7 @@ func (t *Tags) firstTag(keys ...string) string {
 }
 
 func (t *Tags) Title() string         { return t.firstTag("title") }
+func (t *Tags) BrainzID() string      { return t.firstTag("musicbrainz_trackid") }
 func (t *Tags) Artist() string        { return t.firstTag("artist") }
 func (t *Tags) Album() string         { return t.firstTag("album") }
 func (t *Tags) AlbumArtist() string   { return t.firstTag("albumartist", "album artist") }