The HDR QImageIOHandler plugin only supports the default image orientation (-Y +X) in .hdr files. It mixes up the width and height however, resulting in non-square images not loading.
This fix adds a check for the standard image orientation in the file and returns false (with error message) if that fails.
If it succeeds, it takes the height from the -Y component, and the width from the +X component, resulting in successful loading of the image.
Add autotest images for landscape and portrait HDR (Radiance RGBE) loader
BUGS: 433877
Tested with HDR images from hdrihaven.com
* Loading in KolourPaint works
* Thumbnails in Dolphin work
Reviewed by: aacid
Differential Revision: https://phabricator.kde.org/D23811
