Implement support for DJI D-Log and D-Gamut.

[nick-shaw]

References

https://dl.djicdn.com/downloads/zenmuse+x7/20171010/D-Log_D-Gamut_Whitepaper.pdf

[KevinJW]

As a note, I've found the colour matrix built from the primaries in the white paper, to give more pleasing images over using the ones inside the DNGs when shooting RAW.

Kevin

[thomasmansencal]

Ah this is good to know @KevinJW, we have a DJI camera at work and recently wanted to try it. I'll keep that in mind.