Fix the elevator in Diamond Square

src/p_floor.c

@@ -1805,7 +1805,7 @@ static floormove_t *CreateFloorThinker(sector_t *sec)
 	}
 
 	dofloor = Z_Calloc(sizeof (*dofloor), PU_LEVSPEC, NULL);
-	P_AddThinker(THINK_MAIN, &dofloor->thinker);
+	P_AddThinker(udmf ? THINK_MAIN : THINK_FLOORS, &dofloor->thinker);
 
 	// make sure another floor thinker won't get started over this one
 	sec->floordata = dofloor;

src/p_local.h

@@ -69,6 +69,7 @@ typedef enum
 	THINK_POLYOBJ,
 	THINK_MAIN,
 	THINK_MOBJ,
+	THINK_FLOORS, // thanks diamond square
 	THINK_DYNSLOPE,
 	
 	// Lists after this may exist but they do not call an