support explicitly setting dimensions for stat filter
support explicitly setting dimensions for stat filter

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