User feedback: the corridor arrangement is correct (lng=+12
at screen top in N flight), but the per-tile image and labels
were upside down relative to expectations.
- Image drawing: changed from 180° rotation (-TILE, -TILE on
both axes) to Y-only flip (TILE, -TILE on Y). Image top
(north) now lands at canvas bottom; image bottom (south) at
canvas top. X axis is preserved so image east is still on the
right within each tile.
- N/S labels: swapped so N is at canvas bottom (= image north)
and S at canvas top (= image south).
Richard Zink
5ba7596ced