Creating a reference to SpriteLists upon creation

[Aurimukstis1]

It's been suggested I raise an Issue here for this;

# example
my_scene = arcade.Scene()
my_sprite_list = my_scene.add_sprite_list("my_sprite_list")

Here simply we cannot get the reference for the SpriteList by calling it's creation, because in the Arcade code, it returns a None type
It would be a simple change, making it not needed to write an unnecessary extra line like:
my_sprite_list = my_scene.get_sprite_list("my_sprite_list")

[eruvanos]

I stumbled about the same, so let's change that :)

Do you want to create a PR or should I do it?

[Aurimukstis1]

I stumbled about the same, so let's change that :)

Do you want to create a PR or should I do it?

I have no idea how to, so go ahead.