Improve ATL syntax

use the dedicated xycenter property
avoid setting the previous end-interpolation values before starting the new one, to avoid a jump if the player advances too quickly (also shortens the code)
add subpixel True, even though it doesn't seem very effective
prepare improvement in next renpy version

(cherry picked from commit 8b6627f588)

game/scripts/characters/luna/events/intro.rpy

@@ -71,24 +71,21 @@ label luna_intro_E1:
 
     $ luna.set_face(mouth="soft", eyes="closed", eyebrows="low", pupils="mid")
     show CG luna as cg zorder 17:
-        align (0.5, 0.5)
-        pos (-520, -300)
+        xycenter (-520, -300)
     with fade
 
     gen "Who is--"
     show CG luna as cg zorder 17:
-        align (0.5, 0.5)
-        pos (-520, -300)
+        subpixel True
         easein_quad 5.0 pos (-520, 150)
 
     gen "... A girl?"
     lun "*Mmh*"
 
     show CG luna as cg zorder 17:
+        subpixel True
         zoom 1.0
-        align (0.5, 0.5)
-        pos (-520, 150)
-        easein_quad 3.0 align (0.0, 0.0) pos (0, 0) zoom 0.5
+        easein_quad 3.0 align (.0, .0) pos (0, 0) zoom 0.5 # pos (0, 0) not necessary in next renpy version
 
     gen "What are you doing in my office?"
     gen "Did Snape send you here? Surely--"