Added result conversion for RefMany[obj] where a WritesRJ is available

This allows us to omit some boilerplate from controllers that stream an
enumerated RefMany.
Client code for the index of entries looks up the addedBy user for each entry.
Added updateAndFetch, updateSafe, updateUnsafe methods to FindById

This allows us to remove some boilerplate from the database classes.
Enable up-down voting for content entries

Also introduces a pfFor partial in the JSON conversion for
ContentItems, as for instance ContentSequence needs to pass on the
Approval to its child ContentEntries so they can work out the
permissions they offer the user.
Fixed typo in viewingContent that caused error updating content in-place in sequences