Fix playlist shuffle

- Shuffle all indexes
- Use persistent indexes to store play history
- Update virtual items to keep original shuffle order when the playlist is reordered
- Make sure to always set virtual index on manual shuffle
- Ignore repeat and shuffle when dynamic playlist is activated

Fixes #707
Fixes #1381
Fixes #1366
Fixes #1353

src/playlist/playlistsequence.h

@@ -68,8 +68,6 @@ class PlaylistSequence : public QWidget {
   QMenu *repeat_menu() const { return repeat_menu_; }
   QMenu *shuffle_menu() const { return shuffle_menu_; }
 
-  void set_dynamic(const bool dynamic) { dynamic_ = dynamic; }
-
  public slots:
   void SetRepeatMode(const PlaylistSequence::RepeatMode mode);
   void SetShuffleMode(const PlaylistSequence::ShuffleMode mode);