I was looking for official Scrypt reference implementation's code repository, but couldn't find, seems there isn't any? That's awful, this is 2014 year and source control (SCM/VCS) is a MUST have. It's unbelievable that people just work with tarballs without any history/changelog and such. It doesn't matter which you use, but it must be available, otherwise I don't feel like contributing at all, because sending patches over email is too much last century.
I would suggest using Git, but any other would be fine too like Mercurial, Bazaar or even Subversion. Also I would suggest using GitHub for code hosting, but Bitbucket or Gitorious would also be fine, or you might host it yourself on your own server.