Impressive - makercam did a nested pocket. This could be very useful. Looks like the arc g_codes are in absolute mode.
https://launchpad.net/partkam
Use in tandem with http://svg-edit.googlecode.com for an improved drawing experience.
Svg edit looks great. Thanks for sharing.
Found a similar resource here: http://jscut.org/jscut.html - looks to be a little more fleshed out and currently being developed.