Use more central world definition

GeoModelExamples/GeoActions/main.cpp

GeoModelExamples/GeoActionsCountNodes/main.cpp

...oFullPhysVol/step1_create_store_geo_and_publish_nodes.cpp

GeoModelExamples/HelloGeoReadNodeAction/main.cxx

...lExamples/HelloToy/step2_read_geo_and_published_nodes.cpp

...amples/HelloToyXML/step2_read_geo_and_published_nodes.cpp

...VP1GeometrySystems/VP1GeometrySystems/VP1GeometrySystem.h

...isualization/VP1GeometrySystems/src/VP1GeometrySystem.cxx