[Cin] mxf muxing presets

[Andrea paz]

Great; the mxf format was missing. Thanks.
I created 3 renders: DNxHR_Lb; avc_intra and mpeg2. All 3 worked fine
(to me the renderings without render farm go in single thread, instead
in the case of avc_intra it went in multi thread, hurrah).
I've imported the produced files without problems in OpenShot and
Olive; it gives me an error in Kdenlive (the same error I had
importing the CMX3600 EDLs. I guess I don't know how to import files
in Kdenlive...).
Thank you Andrew.