* Upgrade ExoPlayer to 2.18
* Change the position polling from every 2 to every 5 sec
* Make internalMediaItems non-nullable
* Clean up mpv track names
* Reduce explayer ffmpeg extension size by not including all decoders
Removed decoders vorbis, opus, flac, pcm_mulaw, pcm_alaw, mp3, aac because these are already supported by Android.
* Clean up preferredLanguage preferences
* Display downloaded episodes by series
* Add offline playback to readme
* Remove accidentally commited changes
* Remove duplicate movie section in downloadviewmodel
* Fix issues with merging upstream
* Notify on download completion
* Fix trash icon color
* Update DownloadSeriesFragment to use new UiState system
* Clean up unused code
Co-authored-by: Jarne Demeulemeester <jarnedemeulemeester@gmail.com>
