I finally updated Qt Versions in wiki and all links should be reachable (qt.io subdomains, web.archive.org or ftp.informatik.hu-berlin.de are used). It still covers only 4.x, but I may add 5.x-related sections one day.

I know that usefulness of this page is possibly close to 0 now, as most Qt devs are on 5 now, but I believe we should keep track even of old stuff.