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

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