What is the proper way to use to_svg() in rois.py?

[andrewolaughlin]

I know this file came from the vertexrois branch. My overall goal is to get a mask or any volume data and turn it into a roi

My method of getting to_svg to work involves bringing some functions it references back from the dead. I'm guessing I'm doing something wrong. If not I'll put in a pull request tomorrow for review