Add 'BitboardIterator::new'

src/board/bitboard/iterator.rs

@@ -1,6 +1,14 @@
 /// An [Iterator](std::iter::Iterator) of [Square](crate::board::Square) contained in a
-/// [Bitboard](crate::board::Bitboard).
+/// [Bitboard].
-pub struct BitboardIterator(pub(crate) u64);
+use crate::board::Bitboard;
+
+pub struct BitboardIterator(u64);
+
+impl BitboardIterator {
+    pub fn new(board: Bitboard) -> Self {
+        Self(board.0)
+    }
+}
 
 impl Iterator for BitboardIterator {
     type Item = crate::board::Square;

src/board/bitboard/mod.rs

@@ -91,7 +91,7 @@ impl IntoIterator for Bitboard {
     type Item = Square;
 
     fn into_iter(self) -> Self::IntoIter {
-        BitboardIterator(self.0)
+        BitboardIterator::new(self)
     }
 }