Played items should not be automatically removed from the queue

**Current behavior:**
Once a media item is played, it is automatically removed from the media queue. It is no possible to push *previous* button and play it again once its reproduction is over.

**Whished behavior:**
Once a media item is played, it is **not** automatically removed from the media queue.
An index with the currently playing/paused item is held and updated each time. When pushing *previous* button twice, it should be decremented and the previous item in the queue played again.

Media items are manually removed from the queue, using the *trash* button.