4.0: Convert Sprite references to Sprite2D

Some screenshots will need to be updated so that the scene structures shown
in screenshot fit what the code blocks are referring to.

tutorials/math/interpolation.rst

@@ -43,7 +43,7 @@ Here is example pseudo-code for going from point A to B using interpolation:
     func _physics_process(delta):
         t += delta * 0.4
 
-        $Sprite.position = $A.position.linear_interpolate($B.position, t)
+        $Sprite2D.position = $A.position.linear_interpolate($B.position, t)
 
 It will produce the following motion:
 
@@ -89,7 +89,7 @@ Interpolation can be used to smooth movement, rotation, etc. Here is an example
     func _physics_process(delta):
         var mouse_pos = get_local_mouse_position()
 
-        $Sprite.position = $Sprite.position.linear_interpolate(mouse_pos, delta * FOLLOW_SPEED)
+        $Sprite2D.position = $Sprite2D.position.linear_interpolate(mouse_pos, delta * FOLLOW_SPEED)
 
 Here is how it looks:
 

tutorials/math/matrices_and_transforms.rst

@@ -235,7 +235,7 @@ Putting it all together
 ~~~~~~~~~~~~~~~~~~~~~~~
 
 We're going to apply everything we mentioned so far onto one transform.
-To follow along, create a project with a Sprite node and use the
+To follow along, create a project with a Sprite2D node and use the
 Godot logo for the texture resource.
 
 Let's set the translation to (350, 150), rotate by -0.5 rad, and scale by 3.