schemas/util.sql: added lat_long_in_new_world()

schemas/util.sql: added operator @(postgis.geography, postgis.geography). can't use && for this because it only compares 2D bounding boxes (which are geometry objects that do not support geocoordinate wraparound).

schemas/util.sql: added point()

schemas/util.sql: new_world(): removed no longer needed cast to postgis.geography

bugfix: schemas/util.sql: bounding_box(): must use postgis.geography (instead of postgis.geometry) because that handles geocoordinate wraparound correctly

bugfix: schemas/util.sql: bounding_box(): need to explicitly set SRID to make sure the correct value is used

bugfix: schemas/util.sql: bounding_box(): use st_makeenvelope() instead of st_makebox2d() because st_makebox2d() doesn't support geocoordinate wraparound (it is not SRID-aware)

schemas/util.sql: new_world(): removed no longer needed cast to postgis.geometry

schemas/util.sql: bounding_box(): return postgis.geometry instead of postgis.box2d because box2d is not directly used in postgis functions

bugfix: /Makefile: mk_db: plpython3u: use CREATE EXTENSION instead of createlang so that the plpython3u extension is created in addition to the plpython3u language (as it is on Linux)