lpdraw pkg: flip graph along y-axis

Also conditionally enable pixel on screen

Author: ubaidsk

integration_tests/lpdraw/draw.py

@@ -5,7 +5,8 @@
 W = TypeVar("W")
 
 def Pixel(H: i32, W: i32, Screen: i32[H, W], x: i32, y: i32) -> None:
-    Screen[y, x] = 255
+    if x >= 0 and y >= 0 and x < W and y < H:
+        Screen[H - 1 - y, x] = 255
 
 def Clear(H: i32, W: i32, Screen: i32[H, W]):
     i: i32