script reformated / scaling, positioning, units fixed

I've tested your exporter script for using it with the Lasersaur, and it's seems to be very useful (since UV unwrapping never works in the right scale...)

But I got some troubles with an error message showing up in Blender, when exporting the SVG... (something about line 103).

It seemed to be a problem with the formatting (missing tab in Pyhton) I think... Then I've tested it, and needed to change the scaling (curve.dimensions...) and tried to export it directly in millimeters... Hope it works!

What would be great too: switching the Inkscape document directly to mm units...
  <sodipodi:namedview
.......
     units="mm"
     inkscape:document-units="mm" />

But that's is for later, need some sleep ;)