[Cin] exportEDL, timecode patches

[Andrea paz]

1- I created 2 projects in mp4 and ProRes. I exported to EDL CMX3600.
Imports into other programs seem to improve, but always end in error:
In Kdenlive I no longer have the generic error I had before, but I do
have python errors; see images.
In Olive same error as before; see image.
In OpenShot it can't find the original source and it doesn't open (as
before), but it gives the idea to recognize the format.

2- I imported in CinGG an mp4 at 120 fps, edited it with cuts, ffmpeg
filters and transitions; then I rendered in DNxHR_proxy.mxf. All OK. I
imported the files in other NLEs: all OK. I played them in different
players: all OK. (but also in the preceding tests I had not had
problems).
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