Also:
(4)
In v3.8, enabling greyscale output will no longer force the bit depth to
16 bits per channel.
(5)
In v3.8, the `+F` option will allow specifying both the `G` greyscale
flag and the bit depth, using the format `+FxGn`.
(6)
In v3.8, when creating a greyscale image, the preview display _will_
show the image in greyscale.
