Both on_square_clicked and flood_mark were very similar so I've
introduced the on_square_clicked_impl function which is now
called by on_square_clicked and flood_fill.
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
Rather than having the first click hit a bomb, if the first click would
hit a bomb, instead, reset the game board.
This is a (sort of) feature of Windows minesweeper, and IMO makes
playing a bit more fun :-)
Someone was playing this game and suggested a number of improvements so here
we go trying to address them:
- Add "chording" support, where you can click a numbered square using both
mouse buttons simultaneously to sweep all non-flagged adjacent squares.
- Mis-flagged squares are now revealed as such on game over, with a special
"bad flag" icon.
- The game timer now shows tenths of seconds. It also doesn't start until
you click the first square.
- Add the three difficulty modes from the classic Windows version.
