Honour EXIF rotation flag (if present)

[led]

Occasionally an image is imported that was taken while the camera/phone was rotated. The EXIF flag encodes that rotation, but in DBv3 it requires manual intervention to rotate the image.

It would be nice if DBv3 honours the EXIF rotation flag and automatically rotates the image the appropriate amount if required on import.

It's really not a big issue, just a nice-to-have.