Reduce size of eval to i16

src/search/move_ordering.rs

@@ -5,7 +5,7 @@ pub fn score_move(
     mv: Move,
     killer_move: Option<Move>,
     tt_move: Option<Move>,
-) -> i32 {
+) -> i16 {
     if Some(mv) == tt_move {
         return -100;
     }
@@ -15,9 +15,11 @@ pub fn score_move(
     }
 
     let aggressor = mailbox.piece_at(mv.src()).expect("No aggressor found.");
-    mailbox.piece_at(mv.dst()).map_or(100, |victim| {
-        aggressor.0.idx() as i32 - (victim.0.idx() * 8) as i32
-    })
+    if let Some(victim) = mailbox.piece_at(mv.dst()) {
+        return (aggressor.0.idx() - 8 * victim.0.idx()) as i16;
+    }
+
+    100
 }
 
 #[cfg(test)]