Set some circles/messages as favorite

What needs to be done?

When the number of circles and users grows, it's difficult to look for the one I am active on today. I would like to have a "Favorite" main menu where I can pin circles, projects or users so that I do not waste time to look for it.

Technical details

This will need a user interface to put something (circle, user, project, ...) in favorite, and to remove it. I think we need some UX work on this one.