Controller is now in charge of setting cell's color in wrong insertion cases. Some procedures such as set_cell are now obsolete. The features in controller class should be used instead.
Merge branch 'master' of https://github.com/nmaguirre/eiffel-sudoku
After each insertion deletion Sudoku_Board now checks if red cells should be painted back to normal color (which happens when they are not in conflict anymore)
Merge branch 'vostro'