Move naive move generation into sub-module

src/movegen/naive/mod.rs

@@ -0,0 +1,14 @@
+pub mod bishop;
+pub use bishop::*;
+
+pub mod king;
+pub use king::*;
+
+pub mod knight;
+pub use knight::*;
+
+pub mod pawn;
+pub use pawn::*;
+
+pub mod rook;
+pub use rook::*;