tomograph: added aggr.avg() & aggr.subavg() ("-a" mode, only)
tomograph: added aggr.avg() & aggr.subavg() ("-a" mode, only)

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb