tested 20+ generated boards with the board checking function
* corrected a bug in the column checking
* removed a console.log
Correcting a hovering bug when editing a cell
Better user experience, no need to press enter to enter a value
* selecting a cell and typing a value add a value to the board, without pressing enter
* better column checking function, using the internal matrix
* when the board is complete, it will slowly turn to green, indicating that the game is over