First ffmpeg reader

Promised 2 years ago at Siggraph to push my oiio/libquicktime reader :-) finally had som time to put together a more portable ffmpeg version. This is a first version and I don't consider final as-is.
Do you think "mov" is the right 'format name'?

I think we should either call it "movie", or we should actually try to print the true format of the opened file (and "movie" if no file is currently opened or it can't tell).