Good ideas we didn't have time for

[Powersource]

Did we want to make a doc for this? Anyway noting down here for now so we don't forget.

1. We wanted to put re-additions (addition to new epoch after exclude) but we ended up putting all add-member messages on the additions feed because
   1. There was a box2 bug Triangles should be constructed when new feeds are discovered ssb-box2#30
   2. As is also described in that bug, due to triangulation, you can only re-add someone if they've created their epoch feed for that epoch. This is a harder design problem, would maybe require scrapping triangulation
2. As discussed in here Add oldSecrets field to add-member private-group-spec#33 , it's maybe smarter to put oldSecrets in epoch inits instead of in every new addition of a member. Probably slightly more complex though, but saves storage/bandwidth