Use code-generation for some tedious array fill functions
Move a computation out of an inner loop in the renderer
Clean up the renderer a little
Renderer is now produced via generated code

This greatly reduces the amount of code to keep track of, and lets me
specify the rendering process in great detail. It is a first step toward
something resembling programmable shaders (but compiled in rather than
built at runtime). It also makes me much more confident that there are
no undiscovered typos in the rendering engine.
Always generate sources before generating documentation