never add to cache from random iterator
never add to cache from random iterator

Conflicts:
	src/filters/Cache.cpp

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