schemas/util.sql: lat_long_in_new_world(): use new contained_within_approx(geocoord, geography)

schemas/util.sql: added contained_within_approx(geocoord, postgis.geography), which enables specifying just `(lat, long)` without the ::util.geocoord type specifier

schemas/util.sql: OPERATOR (postgis.geography, postgis.geography): renamed to ~ because it's approximate

schemas/util.sql: contained_within(): renamed to contained_within_approx() because the latitude lines of geography type bounding boxes bulge outward, creating false positives above and below the bounding box

schemas/util.sql: added contained_within__no_dateline(geometry, geometry) and corresponding operator @

schemas/util.sql: contained_within(): renamed to contained_within_approx() because the latitude lines of geography type bounding boxes bulge outward, creating false positives above and below the bounding box

schemas/util.sql: geometry(geocoord): documented that it is not possible to create a cast for this, as a bug in pg_dump prevents the cast from being exported, even when no export filters are applied

schemas/util.sql: point(geocoord): renamed to geometry(geocoord) since this is now a cast

schemas/util.sql: point(): return geometry instead of geography to support using points with geometry arithmetic

schemas/util.sql: point(): take a single util.geocoord param instead of separate lat/long