do a proper check to find out of PointSourceId dimension is available for #193
do a proper check to find out of PointSourceId dimension is available for #193

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