Predefined language for subtitles

[valeneri]

The idea here is to set english subtitles as the default langage when launching a video.

We could also store the last subtitle langage selected in client cache with localStorage and set it as the default langage, if changed, after next connection.

In the future, it may be nice to let the user choose whether or not he wants to set a default langage.

[xavierfav]

I think this is a very nice feature! It would be possible to store a default subtitle language in database as a user preference column.