#1494: move parent table creation to a function so logic is in single place, add...

#1494: move parent table creation to a function so logic is in single place, add a new census_loader.sql script with census specific load logic, revise create and update scripts to load the new census logic and create tables if not present. Still need to test and write a function to return census info given a point before can mark this as done.

git-svn-id: http://svn.osgeo.org/postgis/trunk@9147 b70326c6-7e19-0410-871a-916f4a2858ee