Add VERSION for release

No idea what the correct workflow is for these things. In any case, we
somehow have to make the github release system to include the correct
version in its tarball. I don't think you can provide your own tarballs
either, so it has to be in git.

demux_lavf: blacklist "tty" libavformat demuxer

This is completely useless, and in this particular case, it broke the
fallback for MLP2 subtitles (stored as .txt files) to demux_subreader.
(Yes, libavformat should be fixed to handle this, but for now this will
_always_ break playback of subtitle files stored in .txt.)

You can still force this demuxer, but by default we will just pretend
that the "tty" demuxer does not exist.

This version still works with the Libav 0.8.x relases, and some older…

… FFmpeg releases as well.