Performance improvements and bug fixes

Performance improvements.

San Francisco — a seventh city. Includes cable cars, BART and ferries. It opens once you've unlocked the full game and scored 1,000 in every other city. Level crossings. Lay tram track across a road and the crossing gets barriers and flashing lights. Trams take priority, and cars get their turn in the gaps. Tram bridges. Lay track straight into water to throw a tram bridge across for one bridge permit. Draw a road over it later and the two share the deck. Route waypoints. Pin a bus or tram line through the streets you choose, right in the line editor. Track and tunnels have their own stock. Tram track can now run across open ground, not just along roads, and road tiles are scarcer, so each one counts. The tram and tube reward cards bring 12 track or 10 tunnel tiles. 4× speed, for the quiet stretches. Clearer buildings: every city's destinations are redrawn to read at a glance, even on iPhone.