This program is similar to ping(1), but tests connectivity at the
link layer (layer-2) instead of the network layer (layer-3).

HPUX has linkloop support for ages, and lately I googled a little
and found that link-layer connectivity loopback testing is part
of the IEEE 802.2LLC standard.

So I went and written:
	- linkloop for Linux.
	- linkloop_reply as a user space reply program. Used for
	  testing against Linux until the Linux kernel has native
	  support for this protocol (in my TODO :-)
	- lanscan is a small utility to show local interfaces
	  with their mac addresses. Yes I know 'ip link' gives
	  the same information, I just wanted to play with some
	  ioctls :-)

To get me started I grabbed some examples from spak
	http://www.xenos.net/software/spak/
(Which wasn't compiling cleanly on my machine BTW).

It was tested against HPUX-11.0 and Linux (when running linkloop_reply)
both ways.

My linkloop accepts MAC address in:
	- HPUX notation (0x......)
	- Colon separated (00:BC:.....)
	- A name from /etc/ethers