geo_wkb_get_data() fails when parsing Postgis EWKB

geo_wkb_get_data() fails when parsing Postgis EWKB format, which is returned by GeoSQLPostGIS::asBinary() function.

For example, geo_field('load', ...) gets its data using database-specific $geo->AsBinary(), which returns EWKB in case of PostgreSQL. I'm not sure if Geo module itself attempts to parse it anywhere, but developers wanting to use Geo API to process Geo fields data in e.g. hook_nodeapi() seem to need this.

Patch attached.