Fanout should live-update cells without wiping state

[raymondberg]

There's a bit of an odd state you can get into where a fanout has been completed, but the section ids are incorrect because they were last pulled from the server. a837ad6

The way to solve that is by updating the sections locally as they get a fanout request, but that's tricky to do while editing the page.

Try doing fanout on page loads or figure out a complicated way of saving section state while simultaneously loading new section indexes quietly.