Use album artist name for importing downloaded

i.e. if the artist is "OutKast feat. Killer Mike" on the track, and the
album is under OutKast, this will import it under the latter instead of
the former.

README.md

@@ -49,6 +49,7 @@ Doing so isn't fatal (it's not a secret), but it is annoying for other contribut
 * Don't show 404 messages to avoid noise w/ ID migrations
 * Avoid hitting download endpoint if unneeded
 * HTTP timeouts are now handled correctly
+* Use remote album artist name when importing downloaded tracks
 * Fix tracks unable to be downloaded from Subsonic servers
 * Fix a crash when trying to play an album without any tracks
 * Fix a crash if the track's duration is nil

Submariner/SBImportOperation.swift

@@ -69,7 +69,10 @@ import UniformTypeIdentifiers
         if let remoteTrack = remoteTrack {
             titleString = remoteTrack.itemName as String?
             artistString = remoteTrack.artistName as String?
-            if let albumArtistMaybe = remoteTrack.artistName as String?,
+            // first case is so that it matches the album's artist on the server
+            if let remoteAlbum = remoteTrack.album, let remoteAlbumArtist = remoteAlbum.artist {
+                albumArtistString = remoteAlbumArtist.itemName
+            } else if let albumArtistMaybe = remoteTrack.artistName as String?,
                albumArtistMaybe != "" {
                 albumArtistString = albumArtistMaybe
             } else {