Reorganize projects & contributions

[nt1m]

For logged in users, projects will become the new homepage, and instead of one single contributions page, the projects page will link to a per-project contributions page.

[jankeromnes]

Thanks a lot for filing this issue! I totally agree that we should keep track of our ideas in this direction. However, this issue title and description are very vague, so I don't think they're very valuable to people other than ourselves.

And if we expand this issue to include various UX mock-ups, I think that this discussion would make a lot more sense on our Discourse forum than in this GitHub issue (because we'll be doing several back-and-forth discussions, and I feel that GitHub issues aren't great for that).