I'm saving this to the repo so I can possibly come back and fix it up
correctly.
A major API change is going to be attempted. The iterator-based stream
processing has proven to be fiddly and annoying, so I'm going to switch
to a processing the complete image.
Wow, what a mess. Why was I making one giant file to contain everything?
I'm splitting it out into several files and taking another crack at
completing the decoder.
