- xc:white no longer creates a black PNM image.
- Sync pixel cache for -kmeans option.
- Thread -kmeans option.
- PSD: only set the alpha channel when type is not 0.
- Fix Lab to custom profile (CMYK or RGB) conversion bug.
- Inject image profile properties immediately after the image is read.
Signed-off-by: Pierre-Yves <pyu@riseup.net>