FFmpeg 4.0

Just a short post about the latest FFmpeg release. I tried building jjmpeg 3.0.1 against FFmpeg 4.0 and it compiles cleanly with no warnings.

So I think it should be good enough to go ... but I realised I don't actually have anything handy already written to test it against right now so that's only a guess.

Once I do i'll bump the version and do another release. This is more or less what I had planned to do today but instead got tags working on this site instead.