v4.0.0

Changed

• BREAKING: game.move() returns Movement[] instead of MoveResult. Each
  movement is { from, to, piece } where from or to can be undefined
  (piece appearing or disappearing from the board).
• BREAKING: game.undo() returns Movement[] | undefined instead of
  MoveResult | undefined. Movements are reversed (from/to swapped) and include
  uncaptures (pieces reappearing) and depromotions (queen disappearing, pawn
  reappearing).
• BREAKING: game.redo() returns Movement[] | undefined instead of
  MoveResult | undefined.
• Move and PromotionPieceType types are now imported from @echecs/position
  instead of defined locally.

Added

• Movement type exported from @echecs/game.

Removed

• BREAKING: MoveResult type removed. Use Movement[] instead.