[board] Rename the moves modules → move_generator

Update the imports.
Also update some references to crate symbols in move_generator macros to use $crate.

board/src/move_generator/move_set.rs

@@ -0,0 +1,68 @@
+use crate::{piece::PlacedPiece, BitBoard, Move};
+
+struct BitBoardSet {
+    quiet: BitBoard,
+    captures: BitBoard,
+}
+
+struct MoveListSet {
+    quiet: Vec<Move>,
+    captures: Vec<Move>,
+}
+
+/// A set of moves for a piece on the board.
+pub(super) struct MoveSet {
+    piece: PlacedPiece,
+    bitboards: BitBoardSet,
+    move_lists: MoveListSet,
+}
+
+impl MoveSet {
+    pub(super) fn new(piece: PlacedPiece) -> MoveSet {
+        MoveSet {
+            piece,
+            bitboards: BitBoardSet {
+                quiet: BitBoard::empty(),
+                captures: BitBoard::empty(),
+            },
+            move_lists: MoveListSet {
+                quiet: Vec::new(),
+                captures: Vec::new(),
+            },
+        }
+    }
+
+    pub(super) fn quiet_moves(
+        mut self,
+        bitboard: BitBoard,
+        move_list: impl Iterator<Item = Move>,
+    ) -> MoveSet {
+        self.bitboards.quiet = bitboard;
+        self.move_lists.quiet = move_list.collect();
+
+        self
+    }
+
+    pub(super) fn capture_moves(
+        mut self,
+        bitboard: BitBoard,
+        move_list: impl Iterator<Item = Move>,
+    ) -> MoveSet {
+        self.bitboards.captures = bitboard;
+        self.move_lists.captures = move_list.collect();
+
+        self
+    }
+
+    /// Return a BitBoard representing all possible moves.
+    pub(super) fn bitboard(&self) -> BitBoard {
+        self.bitboards.captures | self.bitboards.quiet
+    }
+
+    pub(super) fn moves(&self) -> impl Iterator<Item = &Move> {
+        self.move_lists
+            .captures
+            .iter()
+            .chain(self.move_lists.quiet.iter())
+    }
+}