Fix some imports in the moves package

Castle and EnPassant moved to the board package. Reference these types there.
Add the board packages as a dependency to the moves package.

board/src/lib.rs

@@ -1,10 +1,10 @@
 // Eryn Wells <eryn@erynwells.me>
 
+pub mod castle;
 pub mod en_passant;
 
 mod board;
 mod builder;
-mod castle;
 mod display;
 mod flags;
 mod macros;