BIG structural commit: store "halt" in grund_t, not in plan_t.  Allows for different owners of stations stacked on top of each other (though this feature is not yet implemented).  Also, store 3d "last stop" position in vehicles (necessary as a consquence).  Eliminate resulting dead code.
Bump version to 12 to enable proper save of 3d "last_stop_pos".
Merge branch 'stacked_stations' of git://github.com/neroden/simutrans.git into stacked-stations
Rearrange grund_t data to optimize aligned access
Merge branch '11.x' into stacked-stations

Conflicts:
	simversion.h
Merge branch 'stacked_stations' of git://github.com/neroden/simutrans.git into stacked-stations
CODE: Preparatory changes for passenger generation overhaul
Merge branch '11.x' into passenger-generation
CODE: Addition of code to add buildings to universal world lists.
TODO: Make this work properly with factories - currently fails.
Merge branch '11.x' into stacked-stations
FIX: Attempted to add factories to the world lists before they were built properly
TODO: Properly calibrate the passenger levels.
ADD: First pass at full implementation of new passenger generation code. Still needs work and calibration. Features:
	- Passengers/mail packets are generated globally, not city by city
	- Passengers generated only in residential houses
	- Passengers head for commercial/industrial buildings (that is, both "industries" and industrial city buildings) (TODO: Allow some passengers to head for other residential areas)
	- Mail is generated in all building types
	- Replace local/midrange/longdistance passengers with commuters and visitors, with no distance restrictions, but different journey time tolerances
	- The current "target factories" system is replaced by and subsumed into this system.
	- Resulting code simplification in many areas (TODO: Remove depracated code)
TODO: Add various simuconf.tab customisations.
TODO: Allow onward as well as return journeys
TODO: Add feature to limit number of times commuting trips can be made to buildings in any given month based on the number of jobs that they provide (conceptually tricky - needs further thought, but important).
TODO: Store the private car ownership statistics in the world, not every city
TODO: Allow more than 15 alternative destinations, and allow number of alternative destinations to vary dynamically with map size
FIX: Some memory corruption errors.
FIX: Incorrect numbers of buildings being logged on map generation/refurbishment.
CHANGE: Recalibrate the level of passengers/mail to match the previous oveall level.
FIX: Passenger success rates were not properly recorded.
CHANGE: Depots now function as targets for mail and commuters.
CHANGE: Station extension buildings are now commuter and mail targets.
CODE: Attempt (commented out as it failed) to have dynamic allocation of alternative destinations
Merge branch '11.x' into passenger-generation