Add State struct as part of Board struct

src/fen.rs

@@ -5,7 +5,7 @@ use String as FenError;
 pub fn from_fen(fen: &str) -> Result<Game, FenError> {
     let fen_parts: Vec<_> = fen.split_whitespace().collect();
 
-    let board = piece_placement(fen_parts[0])?;
+    let mut board = piece_placement(fen_parts[0])?;
 
     let side_to_move = side_to_move(fen_parts[1])?;
 
@@ -17,16 +17,14 @@ pub fn from_fen(fen: &str) -> Result<Game, FenError> {
 
     let fullmove_counter = fullmove_counter(fen_parts[5])?;
 
-    Ok(Game {
-        board,
-        state: State::load_state(
-            side_to_move,
-            castling_ability,
-            en_passant_target_square,
-            halfmove_clock,
-            fullmove_counter,
-        ),
-    })
+    board.set_state(State::load_state(
+        side_to_move,
+        castling_ability,
+        en_passant_target_square,
+        halfmove_clock,
+        fullmove_counter,
+    ));
+    Ok(Game { board })
 }
 
 pub fn piece_placement(pieces: &str) -> Result<Board, FenError> {