Add support for win32 link-layer send and receive.

Find portable function to get interface MAC address.

Investigate response packets >60 bytes long, e.g. Windows 2003 Server and
some Cisco.

MPLS tag support (Label Distribution Using ARP: draft-kompella-mpls-larp-11).

Add support for Cisco ISL VLANs in addition to 802.1Q VLANs. Suggested by
Daniel at commonexploits.
