Unfavoriting talks within favorited series

[poonen]

It would be nice if there were some way to unfavorite talks within favorited series, since I may want to continue to receive new talks in those series while removing from my calendar those talks in the series that I know I will not be attending. It may require a discussion to figure out what the user interface for this could be.

[poonen]

I'm making this High Priority just because it is the feature I personally want most at the moment. Of course it can wait until the "test" branch is merged, however. Feel free to remove the "High Priority" tage if you want.