Allow use of SC40 Simon Greener package to export spatial data. When used it replace call to SDO_UTIL.TO_WKTGEOMETRY() by SC4O.ST_AsText(). Thanks to Dominique Legendre for the suggestion.
Add USE_SC40_PACKAGE configuration directive to use  SC4O.ST_AsText() instead of SDO_UTIL.TO_WKTGEOMETRY(). Update documentation and add a dedicated Oracle Spatial section.