Improved metadata support via EXIF metadata. Since JXR is based on a TIFF container, EXIF data is read directly from the file so it always works (even with versions of libjxr that don't have the metadata reading API).
It also solves the following issues:
- Incorrect date format on saved JXR files (was saved in ISO format instead of `yyyy:MM:dd HH:mm:ss`).
- Incorrect date type setting in EXIF data: the `DateTime` tag should be updated on every save (verified by GIMP and Photoshop). Our `CreationDate` metadata is the equivalent of the EXIF `DateTimeOriginal` tag.
Closes#22
Qt 6.8 will introduce native support for the CMYK (8-bit) format.
With this patch you will finally be able to correctly see the colors of CMYK images with ICC profile.
The testing part has been updated with the addition of an (optional) json file for each image to test. Inside you enter which image to use depending on the Qt version.
In short:
- Added native CMYK suport to PSD reader
- CMYK with alpha is converted using QColorSpace in a RGBA image
- Read tests changed to use the correct comparison image based on the Qt version
- Fixed also XCF tests: now works with all Qt version (see also [QTBUG-120614](https://bugreports.qt.io/browse/QTBUG-120614))
- Work around for CCBUG: 468288
