add simple i/o testing of the XML schema reader/writer
add simple i/o testing of the XML schema reader/writer

mpgerlek/PDAL-old,verma/PDAL,jwomeara/PDAL,lucadelu/PDAL,lucadelu/PDAL,DougFirErickson/PDAL,Sciumo/PDAL,verma/PDAL,Sciumo/PDAL,boundlessgeo/PDAL,Sciumo/PDAL,radiantbluetechnologies/PDAL,jwomeara/PDAL,jwomeara/PDAL,DougFirErickson/PDAL,verma/PDAL,mtCarto/PDAL,verma/PDAL,mtCarto/PDAL,mtCarto/PDAL,radiantbluetechnologies/PDAL,mpgerlek/PDAL-old,boundlessgeo/PDAL,boundlessgeo/PDAL,lucadelu/PDAL,radiantbluetechnologies/PDAL,mpgerlek/PDAL-old,DougFirErickson/PDAL,DougFirErickson/PDAL,Sciumo/PDAL,mtCarto/PDAL,verma/PDAL,radiantbluetechnologies/PDAL,lucadelu/PDAL,boundlessgeo/PDAL,verma/PDAL,mpgerlek/PDAL-old,jwomeara/PDAL,verma/PDAL