Moving DIBs (device-independent bitmaps) to CGImage

The biggest remaining clot of link errors (probably about 30 or so) relate to Cello's handing of Bitmaps. There are a handful of classes, many parts of which of which are commented out or omitted from compilation, that deal with bitmaps. Hanging on to this are classes and libraries that deal with reading and writing images to and from physical files. Central to all of this is the class that manages the DIB which I have discovered is a device-independent bitmap. The wikipedia article is an excellent introduction and explained why, when I was reviewing the code, I saw code and logic that dealt with vertically flipping images (it seems that DIBs are an inverted format). There is also a fair amount of wrangling to move DIBs (which represents an actual bit image) between images.

My plan here is to replace the DIBs and indeed the image classes with a thin wrapper around CGImage. Apple's ImageIO framework provides a homogenous way to read and write these images in a variety of file-formats.