I've done an initial push to Github, including all the existing SVN history. It turns out that it's not just CodePlex's SVN implementation that has trouble with Unicode filenames, ho hum.
So you can grab the code here:
https://github.com/alexwarren/QuestThis is still experimental at the moment, so the official code repository is still CodePlex for the moment. It should be straightforward for me to keep the github code updated with anything checked in to CodePlex, so the two can run side by side until I decide whether to switch over or not.