• When range2cidr accepts a file, it now also looks to see if there is a
  header in CSV form, and if so changes the first column to cidr, just as it
  changes the first non-header columns from IP ranges to CIDRs. NOTE: this
  will work even if the IP range takes up 2 columns as in start_ip,end_ip,
  in which case both columns are replaced by a single column cidr.