Sudoku Solver

This is a fully working sudoku-solving program.

The program supports reading of specific .sudoku files.
If the user wants to save a solved sudoku, it saves the solved sudoku in a .ssudoku.
-The .ssudoku (Solved sudoku) is formatted with 3x3 boxes. This file is therefore not compatible with the filereader, hence the reason of the change in the filename.

Upcoming:
In the coming releases there will be some code cleaning.
Furthermore, I will try to implement multi-threading to further enhance the speed of the program.