If you like parvis and you want to improve it, just go ahead! Parvis is open source, and as long as you leave the GPL intact and release all your code under the GPL, you are authorized to do whatever you want with the code.
Personally, I will not put much more energy into this project, since it originally started as a university lab exercise and already got bigger than I expected. Also, I think it is a useable program as it is now, be it for computer science or sociology classes (which might be less interested in the source code I suppose). However, I have some more ideas on my "would like to do" list, which I didn't have the time to implement. Here you are (my effort estimates are in [ ]):
Have Fun!