* Add a proc for getting the station center
* Add a couple of comments to ZTRAIT defines
* Remove unused global_map list
* Refactor weather to use the trait system
* Un-hardcode the transit z-level
* Use Z traits to determine Portal Storm event areas
* Fix loading away missions containing anything that reads traits
* Add basic structure of z-level traits
* Restore space transitions and add z-level debug verb
* Restore proper ruin spawning and transit level creation
* Replace station_z_levels and related checks with traits
* Eliminate more uses of ZLEVEL_{STATION_PRIMARY,LAVALAND}