About 4x4 sudoku CAD program.
When developing regular Sudoku CAD I had parameterized all GUI and algorithms and made
sure they will run with 4x4 region size. So this version was almost free. I only had to limit solution tree
scanning for intermediate results when creating new puzzle because there were way too many variants
there (10M+) and 4x4 "monster" Sudoku was ready for real enthusiasts.
