Indexing with ArtistSort

[bganthem]

I tried adding Album to indexTags and, separately, to itemTags (where it now resides) and then entering tagValue strings for Album.value.index.display, but any string commencing with 'Album' is disallowed, and I'm not sure that my strings (eg. ={Album, AlbumArtist, ArtistSort}) would have worked. I also looked at trying to modify AlbumArtist behaviour with AlbumArtist.value.sort.display={AlbumArtist, ArtistSort}, but that does not affect the Album index display.