- display pawn possible attack moves - in puzzles, if we fail but we nevertheless put the opponent in check, the bot plays to show why we failed

fix 3 puzzles that were invalid

add a puzzle mode, with 1200+ puzzles, and more to come.

I've updated moves of the pawns, which now works as follow: - pawns move forward in their "track", just like a rook would do, just one tile at a time. - if the track reaches the end of the board, the pawn can promote as usual. - if the track ends on the left or right side of the board, when the pawn reaches it, it changes track. If there are multiple tracks it can take from there, the one that reaches the end in the least amount of moves is selected - when a pawn captures, it changes track following the same rule. There are 2 reasons for this change. First, I wanted to de-clutter the board and remove those little arrows that were on every tile, whose purpose was only to indicate which direction a pawn could move. And second, it makes the pawns movement much more intuitive. In addition to this, you can now create symmetric boards. In order to do so, when you start a game, in the "Board" settings, you can either: - select "From Our Selection", and pick a board from the "symmetric" category - select "Generate New Board", and toggle the "symmetric" option. I'm hoping symmetric boards can offer an alternative to the currently existing asymmetric boards. And of course, feel free to alternate between the 2, they should be equally compelling.