Add option to automatically remove downloaded episodes once played

[amugofjava]

Is your feature request related to a problem? Please describe. Once a downloaded episode has been fully played, it remains in the Downloads section until you manually remove it. Each episode has to be removed one at a time which can be frustrating.

Describe the solution you'd like A new option 'Remove downloaded episodes once played' should be added to the settings page in the Episodes section. When toggled on, upon reaching the end of playback of an episode which is downloaded to the user's device, it should be deleted.