add positional arguments support for input/output
add positional arguments support for input/output

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