Allow clicking cell numbers to reveal surrounding unmarked cells

[haykam821]

Some Minesweeper versions have a feature where clicking a numbered cell will reveal neighbors. This feature could be implemented to make Minesweeper games faster.

[RealRTTV]

In my experience, it's been done under middle click, I don't think implementing both is the best solution, which do you think would be better?

btw, I can make a quick PR tonight

[haykam821]

I don't have a middle-click button.