range2cidrlist($startip, $endip)
Given a range of IP addresses, return a list of blocks that span that range.
For example, range2cidrlist('216.240.32.128', '216.240.36.127'), will return a list of Net::Netmask objects that corrospond to:
216.240.32.128/25
216.240.33.0/24
216.240.34.0/23
216.240.36.0/25