This is a simple container for 2d CMYK data.
This is a new class instead of a new format in Bitmap because:
* Almost all clients of Bitmap will want to deal with RGB data
* It keeps the ARGB32 typedef working
* Bitmap already does a lot of things
The idea is that a few select places will be able to use
CMYKBitmap and a color profile to do a better CMYK -> RGB conversion
than an image decoder could do, and then store the result in a Bitmap
for later display then.
CMYKBitmap misses some of Bitmap's features, such as shared
memory support, high-dpi scaling capability, etc.
