[Devmon] Initial weather map implementation

[Buchan M. <bg...@st...>]

I have been hacking on the perl versions of weathermap that I found, and have 
hacked one up that works with Hobbit and devmon (for now, only devices using 
the if_load test).

The interface load and descriptions are taken from the if_load test (retrieve 
from Hobbit via hobbitdlog), and the map is created using a configuration file 
(mostly the same format as that used by the other implementations).

The difference is that a lot less information needs to be included in the 
weathermap configuration (the INFOURL, OVERLIBGRAPH, TARGET, BANDWIDTH), as 
they are unnecessary for Devmon/Hobbit.

However, the node names need to match the hostname used in bb-hosts, and the 
interfaces need to be specified with the INTERFACES tag.

E.g., this is sufficient to get two nodes and a link between them, with popup 
graphs of the interface (on the arrows) and load (on the nodes). 

NODE tau
        LABEL TAU
        POSITION 86 524

NODE upsilon
        LABEL UPSILON
        POSITION 421 524

LINK tau-upsilon
        NODES tau upsilon
        INTERFACES Gi1/1 Gi1/1


A tarball is available at: http://staff.telkomsa.net/~bgmilne/devmon-
weathermap-1.1.2.tar.gz for now.

I think sufficient instructions are available, but I would love to hear what 
other people think ...

Regards,
Buchan