/// move_to_uci() converts a move to a string in coordinate notation
/// (g1f3, a7a8q, etc.). The only special case is castling moves, where we
/// print in the e1g1 notation in normal chess mode, and in e1h1 notation in
/// move_to_uci() converts a move to a string in coordinate notation
/// (g1f3, a7a8q, etc.). The only special case is castling moves, where we
/// print in the e1g1 notation in normal chess mode, and in e1h1 notation in