Use the published board instead of drawing a worse one

Three attempts at drawing this map came to nothing worth looking at. Dividing
the plane by nearest province gives a tidy board that looks nothing like
Europe. Drawing the adjacency graph gives something unimpeachable about the
rules and not a map at all -- circles joined by lines. Fifty-six polygons
placed by eye gives fifty-six islands.

The standard map published with the diplomacy engine is AGPL-3.0, the same
licence as this project, so it can be carried across whole with attribution
rather than approximated badly. tools/map.py extracts the outlines, the unit
coordinates and the layer transform into board.json and can be re-run against
a newer copy. NOTICE.md says where it came from and what is still ours, which
is every colour and every mark drawn on top.

Drawing Europe accurately is real work, somebody did it properly, and they
published it under a licence that invites exactly this. Three days of my
approximating it would have produced something worse than the thing that
already existed.

Clicking still answers with the rules rather than the picture: a shape cannot
say that a fleet on Spain's north coast may not enter the Gulf of Lyon while
one on the south coast may, because both coasts are the same shape.

README.md

@@ -35,29 +35,25 @@ would not be.
 
 ## The look and the sound
 
-**Cartoony.** Flat cel fills and one heavy outline, the same house style the
-other three games use, on a map generated from the topology in
-`src/game/map.ts` rather than traced from anybody's board. The coordinates in
-`src/game/layout.ts` are placed by hand -- roughly where each province falls
-in Europe -- and everything else is drawn from those and from the adjacency
-rules.
+**The map is the standard board's geometry, under the same licence as this
+project.** The outlines come from the diplomacy engine at
+<https://github.com/diplomacy/diplomacy>, which is AGPL-3.0, extracted by
+`tools/map.py` into `src/game/board.json`. Every colour and every mark drawn
+on it is ours; see [NOTICE.md](NOTICE.md).
 
-**Territories, with the rules kept out of the picture.** The regions are
-Voronoi cells -- every point belonging to the nearest province -- which
-divides the board with no gaps and no overlaps and looks like a board.
+Three earlier attempts drew it from scratch and all three were worse.
+Dividing the plane by nearest province gives a tidy board that looks nothing
+like Europe. Drawing the adjacency graph gives something unimpeachable about
+the rules and not a map at all -- circles joined by lines. Fifty-six polygons
+placed by eye gives fifty-six islands. Drawing Europe accurately is real work,
+somebody did it properly, and they published it under a licence that invites
+exactly this.
 
-What it cannot do is reproduce every adjacency in the rules, because
-provinces here interleave: the Adriatic borders Venice with Trieste sitting
-between their centres, and the Atlantic borders North Africa round the
-outside of Spain. Convex cells cannot say that.
-
-The wrong lesson to draw from that -- and the one I drew first -- is to give
-up on regions and draw the adjacency graph instead. It is unimpeachable and
-it is not a map; it is circles joined by lines. The right answer is to stop
-asking the picture to carry the rules. **Click a province and exactly the
-provinces its unit may legally reach light up**, taken from the adjacency
-graph itself. The picture is a picture, and the rules answer for themselves
-when they are asked.
+**Clicking still answers with the rules, not the picture.** A shape cannot say
+that a fleet on Spain's north coast may not enter the Gulf of Lyon while one
+on the south coast may, because both coasts are the same shape. So selecting a
+province lights up exactly where its unit may legally go, taken from the
+adjacency graph.
 
 **It gets the whole screen.** The other three games live in a four-by-three
 cabinet because the machines they are rebuilding did. This one is not