This module can be used to create and send ARP packets and to get 
the mac address of an ethernet interface or ip address.

IMPORTANT: Version 1.0 will break with the API of PRE-1.0 versions, 
because the return value of arp_lookup() and get_mac() will no longer 
be passed as parameter, but returned! I hope this decision is ok 
as long as we get a cleaner and more perlish API.
