Lot servers handle city disconnects with more grace

[ddfczm]

• Lot servers detect city disconnects and save / shutdown lots
• CityServers now reconnects after a city goes down. This means you can reboot a city without having to reboot the lot servers.
• LotAllocations can now handle a city reconnecting
• Lot servers now release lot locks on shutdown as well as city for cases where the city is offline
• Main thread is no longer shutdown after 4 background loops without tasks. When shutting down no background tasks are generated. If save takes a while this interrupts the save process.
• Bunch of error catches