[kfxrwkql] Remove the directionality of chess

Replace the normal pawn with a piece that moves like a wazir and captures like a ferz.  It does not promote.

The goal is to remove the "directionality" of the chess board.  All pieces now move isotropically.  (Originally inspired how much simpler pawnless endgame tablebases are to compute.  There is a factor of 8 reduction by rotations and reflections.)

Other issues include: en passant, castling, two-square initial pawn move.  The straightforward solution is just to get rid of them but another is to permit them more frequently.

A wazir-ferz pawn may always (not just initial move) make two wazir moves in the same direction, and another pawn may always capture en passant at the intermediate square.  This means in a blocked pair of opposing pawns, if one pawn does a double side-step to try to escape, it faces immediate en passant capture.

Another idea might be to limit the double moves to a hash-symbol shaped set of squares which could have been initial positions, and limit the direction of the double move according where it is on the hash. Squares b1 b7 g1 g7 then become special, allowing double moves in two directions. Maybe double moves in the a h files and 1 8 ranks, too?

A rook in any corner and a king in the appropriate position on the same rank or file may always swap like in castling.  There is no requirement for neither piece to have moved or not castled already.  Note that one can do queenside-shaped castling on the kingside if the king has moved to d1.