Reworked the AudioEngine (PlaybackService).
Few fixes to the way Queries are persisted in the db.
Only add a track result to a query, if it hasn't been added yet.
Only blacklist results if network available. Otherwise just skip to next track.
Minor graphical glitch workaround in SpotifyMediaPlayer seekTo().
Fixed notification bug, where buttons would become unresponsive.
Prohibit notification from showing up by itself after dismissed.
Resolve queries if skipping to next queries (even if not playing/preparing).