Bug 492048 - Detect color space in Exif 2.21/DCF 2.0 option files

Copy a ton of logic from darktable and libkexiv2 and parse more
metadata tags which contain colorspace information, namely:

Exif.Photo.ColorSpace
Xmp.exif.ColorSpace
Exif.Nikon3.ColorSpace
Exif.Canon.ColorSpace