Hello there,
2.0 is released!!!!
check out the new features here
I started this project when I was a student. It's been a while and I am working now so I don't have the time to continue this any further. However there is one last update. Some exciting new features.
It is now supported for 2017 - 2019
The script renders an additional pass while maya updates the viewport that can be displayed later. I made a nice little introduction so you can see it in action.
If you like it, consider buying it for a few bucks. But it's free and also on github, if that's more to your liking.
https://github.com/Viele/onionSkinRenderer