winFlag

Now when the squares with  mines beneath them are flagged, a JOptionPane will pop up telling the user that they won! There's also a variable that's keeping track of how many flags they have left. But I didn't put an actual limit to it, since minesweeperonline.com didn't either. All that minesweeper does is continue into the negative. But by then the user would know that they've gon too far. I'm keepin git at 20, giving them a hint of how many mines there are, though there's actually less than 20.