use center eucl dist on spawn tiles, looks nicer (#202)

src/core/execution/Util.ts

@@ -1,7 +1,7 @@
 import { euclDistFN, GameMap, TileRef } from "../game/GameMap";
 
 export function getSpawnTiles(gm: GameMap, tile: TileRef): TileRef[] {
-  return Array.from(gm.bfs(tile, euclDistFN(tile, 4, false))).filter(
+  return Array.from(gm.bfs(tile, euclDistFN(tile, 4, true))).filter(
     (t) => !gm.hasOwner(t) && gm.isLand(t),
   );
 }