cleanup agent structs

src/model.rs

@@ -73,9 +73,9 @@ impl Model {
         }
 
         let mut grids: Vec<Grid> = Vec::new();
-        for pop in 0..n_populations {
+        for _ in 0..n_populations {
             let agents = (0..particles_per_grid)
-                .map(|i| Agent::new(width, height, pop, &mut rng, i))
+                .map(|_| Agent::new(width, height, &mut rng))
                 .collect();
             grids.push(Grid::new(width, height, &mut rng, agents));
         }