ADD: Option to enable subtitles by default

Without this option, subtitle users have to enable subtitles in the Audio-Settings menu each time they start a video. Wanted to base the decision on the Languages -> Subtitle mode of the PMS, but cannot find out how to read the setting from the server.

If you have other ideas of how to implement such a function or can give a hint on how to read the setting from the PMS, please let me know. Couldn't find it in the API documentation.