Small updates to platformer tutorial for 3.0 (pythonarcade#2178)

Author: Cleptomania

arcade/examples/platform_tutorial/02_draw_sprites.py

@@ -42,7 +42,7 @@ def on_draw(self):
         self.clear()
 
         # Draw our sprites
-        self.player_sprite.draw()
+        arcade.draw_sprite(self.player_sprite)
 
 
 def main():

arcade/examples/platform_tutorial/09_sound.py

@@ -146,7 +146,7 @@ def on_update(self, delta_time):
             arcade.play_sound(self.collect_coin_sound)
 
         # Center our camera on the player
-        self.camera.center(self.player_sprite.position)
+        self.camera.position = self.player_sprite.position
 
     def on_key_press(self, key, modifiers):
         """Called whenever a key is pressed."""

doc/tutorials/platform_tutorial/step_02.rst

@@ -68,7 +68,7 @@ Now we can draw the sprite by adding this to our ``on_draw`` function:
 
 .. code-block::
 
-    self.player_sprite.draw()
+    arcade.draw_sprite(self.player_sprite)
 
 We're now drawing a Sprite to the screen! In the next chapter, we will introduce techniques to draw many(even hundreds of thousands) sprites at once.