add ability to dump xml metadata for stage
add ability to dump xml metadata for stage

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