Subtitles from fle

This enables pulling subtitles individually from the central server, without unpacking.

With a small client-side change, then subtitles support can continue as it currently does.

Dylan, please merge the latest upstream/develop to see the changes here.

I essentially made a bunch of code review-esque changes while trying to get the scripts to work as I wanted (more robust downloading support, as things fail somewhat easily due to amara badness; paths to where I wanted, testing options that I wanted, etc)

Please ping me when you've done the merge, so I can annotate the changes for you.