Hello,

I have fixed a few bugs and somewhat improved the chess game.

Bugs:

- castling was not possible when a rook was menaced
- a test for king attack in black king-side castling was missing
- the cached number of pawns is sometimes off, which could lead to a 
DivideByZero error in some endgames (this is fixed, but not the 
discrepancy which still effects the material evaluation)
- a pawn taken en-passant was not removed from display

One notable bug left is that undoing a castling move makes it impossible 
to castle again.

Improvements:

- nicer display, scalable (with assets from wikimedia common)
- the board is now sticky and cannot be accidentally grabbed
- hints (from the 'help' button) now appear in the status line
- support for Fischer randomized chess, aka Chess960

Changes:

- to castle, one now has to move the king over the rook


To try it:

	Chess960Morph new openInWorld


Stef
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