Add some missing imports.

chapter-03-walkmap/src/main.rs

@@ -2,6 +2,7 @@ use rltk::{Console, GameState, Rltk, RGB, VirtualKeyCode};
 use specs::prelude::*;
 #[macro_use]
 extern crate specs_derive;
+use std::cmp::{min, max};
 
 rltk::add_wasm_support!();
 

chapter-04-newmap/src/player.rs

@@ -1,6 +1,7 @@
 use rltk::{VirtualKeyCode, Rltk};
 use specs::prelude::*;
 use super::{Position, Player, TileType, xy_idx, State};
+use std::cmp::{min, max};
 
 pub fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
     let mut positions = ecs.write_storage::<Position>();