Add basic support for Microsoft's (!) JPEG XR format.

No metadata support yet, so colours will be off.
Remove some old code that was commented out.

We now create an LCMS2 "format" by getting its "pixel info" instead of using the lookup table.
I don't think we can do the same thing in the opposite direction. We might be able to go through all formats using GetPixelFormatFromHash() and check all of the relevent properties.
Rename some fields/methods in D_JXR and change defaults to more "normal" settings.

Set lossless settings in process_scans.
Add XMP and IPTC metadata to JXR files.

EXIF is commented out for now because it causes a buffer overflow somewhere in jxrlib.
Read and write ICC colour profiles in JPEG XR files.

Damn Microsoft, calling it a "color context".
Fix JXRcheck() macro.
Rename "tilesize" parameter of JPEG XR to "tile".
Wrap the jxrlib calls creating and free objects with try-catch blocks.

Make sure the tile size is only 256, 512, or 1024 pixels.
Add .wdp and .hdp filename extensions for JPEG XR reader.
Read XMP, EXIF, and IPTC metadata from JPEG XR files.

Untested because I don't have any examples!