OK, this made the --sub-paths and --audio-file-paths synonyms, which is
not what we wanted. Actually restrict the type of file loaded as well.
Really fixes#2632.
Requested. It works like --sub-paths. This will also load audio files
from a "audio" sub directory in the config file (because the same code
as for subtitles is used, and it also had such a feature).
Fixes#2632.
This was in sub/, because the code used to be specific to subtitles. It
was extended to automatically load external audio files too, and moving
the file and renaming it was long overdue.
