Added some horse cards:

• Horse Girl - give your Queen the horse she's always wanted.
  
• Horse Thief - Pawn takes horse from a nearby Knight
  
• Knook Upgrade - directly promote a Rook to a Knook
  
• Sigma Knight - upgrades your Knight to move in a straight line and take no more Ls
  

Fixes for J'Adoube Beaucoup allowing you to adjust pieces onto uninhabitable squares, and for Bear Trap being placed directly under a piece.

Altered explosions to be blocked by walls, damage walls, additional underlying mechanics for future use.