THE BIG MERGE, part 2: magfest 8.5 branch into main branch

WIP, obviously this needs a ton of discussion/etc

Around end of July we merged the applicable parts of master-magfest85 branch into master.  Since then there have been a bunch of small fixes and other things that should go into 'master'.

There are also some changes here that should not go into master, such as fixes for groups/etc.

Once this merge is done, the 8.5 branch will go away and we will have only one 'master' branch for uber.
This is all Django code and would need to be rewritten.  I'll keep looking through this PR, but in general I'm probably against doing a big merge like this.