Detailed todos (part of larger optimizations and not listed in the description

of those tasks.

- LLVM probably leaks memory because the module-global variables are never

  destroyed. -> The constant can be destroyed after the function has been

  compiled, or once the pipeline goes out of scope. (This was tried once but it

  caused a crash, possibly an ownership issue.)

- Image rendering might fail if paint matrix is singular

- It might make sense to store the polygon start-winding separately (when edges

  are clipped)

- Investigate if there is some easy way to make the amount of

  intermediate-representation bits definable at compile-time or if it is useful

  in some case.

- Dithering!

- Hooks for changing the framebuffer and/or mask format. Send message to:

  pixel-gen, and lut-gen?

    * This is not required because the state is prepared from scratch every

      time.

- Avoid path retessellation if possible?