vmsd-grapher: Display relations between VMWare snapshots

This is a quick hack to display the relations between VMWare snapshots. I needed this because VMWare Fusion shows the snapshots in a list, instead of a tree view.

The default output mode is ASCII (for VMs with few snapshots). HTML and SVG output can be used for more complex situations. These files can be opened with Safari and Firefox.

The script is called vmsd-grapher and requires Graph::Easy. SVG output also requires Graph::Easy::As_svg.