[SudokuDialog] update main dialog layout to QGridLayout
[SudokuDialog] change open/save from PushButton to ToolbarButton
[SudokuDialog] update buttons layouts, hide listTB
[SudokuThread] add abort variable and method
[SudokuDialog] add abort thread slot
[SudokuDialog] update start() - add abort functionality
[SudokuDialog] delete obsolete abort slot
[SudokuThread] add emit to update progressBar to minimum on start (MEA could worl long time)
[images] replace old icons by new icons