User wants the O/W axis mirrored within each tile. With
the previous Y-only flip, East was still on the right and West
on the left. Adding an X-flip makes it 180° rotation:
- Image North -> canvas bottom, South -> canvas top
- Image East -> canvas left, West -> canvas right
Labels N/S were already positioned at canvas bottom/top to match
the Y-flipped image, so they stay where they are. Tile arrangement
in the corridor is unchanged (still controlled by canvasX/canvasY
formulas with no swap on either axis).
Richard Zink
2f7c09fc16