Bukkit

Fixed a bug related to moving around in the city world.

Renamed the spawn world config option to "city world" for clarity. If you don't have a city, leave it blank.

Added a "Managed World" config option. If you're comfortable with a little initial maintenance, you can have PopulationDensity manage your default world.

When teleportation is disabled, players can still use /homeregion to teleport from the city region to their home, and /cityregion to teleport ONLY from their home to the city (not from any other location).

Added a config variable for how far from the spawn you can be and still use /homeregion (see above note). If teleportation is enabled, this setting doesn't matter.