Finally a break on how I want to do pixel format, I have hashed out
a small file that implemnts the basics of this. I will be trying
out ways of using them for c-arrays, glstructs and gpu-arrays.

* First dump of pixel-format code
* Added the cffi types :byte and :ubyte
* removed the old image-format file as it just contained scraps of
  ideas
* Played some more with example 11, it is pretty cool now