v1.2.0

• solve Sudokus larger than childrens complexity in a less embarassing duration of time
• make argument parser more strict on trailing, unparsed content

Reduced solve time by alternating between deterministic solve and trial-and-error with somewhat clever guessing.

Solve time of 12x12 reference Sudoku (see test/reference_12x12,4x3.txt) down from impossible to 1s.