Build towns and buildings from the atlas

Stage 3 of the world-building plan, done on feat/world-atlas (#103): every settlement has a plan (bands of plots fronting south, cross streets with east-fronting corners, a square and a market, districts, required buildings per tier, free plots for players, octagonal walls with gates where the roads arrive), filled with uo-buildings (#101) and baked into statics.bin (format 2: storeys, roofs and exact heights; upper storeys hide as Overhead). Seed 1: 2665 buildings. Review: walk Skartor and a few villages in the client; follow-ups are town-landmarks (castles, gatehouses, docks, bridges) and townsfolk.