Double jump issue

[Nevesgmd]

As mentioned on this issue, there's a double jump bug whenever the second jump happens on a row < 5. To fix it, just correct the _traverse_left and _traverse_right methods of the Board class passing the minimum value of the max() function as -1.

This: row = max(r-3, -1)

Instead of this: row = max(r-3, 0)