[Cin] Yet another interlace-related patch

[Andrea paz]

>
> I was unable to get dxnhd codec running, it always complained about something :/
> DNxHR still doesn't show up as interlaced ......

What a lot of work you do, thank you very much!
Of the DNxHD codec there are many specifications for each combination
of resolution, bit rate and depth color. It is an unmanageable codec
because it always finds compatibility problems. Basically only Avid
used it. This is why DNxHR was created, which imitates the formats and
flexibility of ProRes.
The only rigidity of DNxHR are 4:2:2 or 4:4:4 (like ProRes) and the
lack of interlacing, it can only be progressive.

PS: There is also another famous high quality format: Cineform (GoPro
property, but open). I've seen that it has big problems of slowness
and compatibility with ffmpeg, so I didn't try to create presets.