TODO List for libhalftoner

Things that need to be done, in no particular order:

• Add framework for other algorithms, such as threshold matrices.

  Currently, only error diffusion and the technique by Velho-Gomez are available.

• Refactor class ErrorDiffusionHalftoner as to take a diffusion matrix.

  Currently, the class abstracts two methods. Experience has shown that the methods have a lot of duplicated code.

• Everything on the TODO list.