The sourceforge repository just disappeared. I've read somewhere they were not against using GitHub, so perhaps they are just moving to GitHub.
I've found there they have also developed GUIs for some tools like map compilation, texture compression etc. It's written in the moddb page that it's idtech2 based game (like Xonotic), so I guess most of Unvanquished and Xonotic developers will feel comfortable to read their code. I hope some improvement can be picked up. :-)
[Edit 2016-09-19]
In their 2010's design document they said the network stack is the one from id tech 3, and in their tool set released in 2011 they talk about Doom3 file structure. Their tools look for pk3. It looks like tools run on wine (not extensively tested but they launch) but the map editor crash at startup on wine.
[Edit 2016-09-22]
The sf.net svn repository reappeared, with a commit today.