[Board] Implement castlingRights and enPassantSquare

Board.cpp

@@ -41,19 +41,19 @@ PieceColor Board::turn() const {
 }
 
 void Board::setCastlingRights(CastlingRights cr) {
-    (void) cr;
+    mCr = cr;
 }
 
 CastlingRights Board::castlingRights() const {
-    return CastlingRights::None;
+    return mCr;
 }
 
 void Board::setEnPassantSquare(const Square::Optional &square) {
-    (void) square;
+    mEPS = square->index();
 }
 
 Square::Optional Board::enPassantSquare() const {
-    return std::nullopt;
+    return Square::fromIndex(mEPS);
 }
 
 void Board::makeMove(const Move &move) {

Board.hpp

@@ -40,6 +40,8 @@ private:
 
     BitBoard mPieceBBs[BB_NUM] = {};
     PieceColor mTurn = PieceColor::White;
+    CastlingRights mCr;
+    unsigned mEPS = 64;
 
     static inline void clearIndex(BitBoard &b, unsigned i) {
         b &= ~(1ULL << i);