#193 Add alternative titles for DLNA clients to show seasons with episodes in title

[Serhii Horelskyi]

Hi all,
I want propose some improves for DLNA clients.
I love watching tv shows from my PS4 console, but when a mount of episodes located in one directory, you can't understand how to watch them, because they are not ordered by seasons and episodes, they ordered only by names because no season/episodes are displayed.
I'm proposing 'alternative titles' option for Audios and Videos. Example:
Audio 'enable_audio_alt_titles=yes': 'My favorite song' -> '1/02 - My favorite song' (disk/track)
Video 'enable_video_alt_titles=yes': 'Amazing story travel' -> 'S01E02 - Amazing story travel' (season/episode)
If all required metadata exist (their id's != 0) and related options are enabled, we use alternative titles for DLNA clients.
It's prepared as patch for debian apt-packages.