DB restructured, order field for interactions

Flattened out the db — each question (whether main or alt) is now its
own record.  No more sub-documents.  Fixed question-related code to
match new structure.  Added an order (o) field on question records.
(Will add to hierarchy records later.)  Added a “Jump to edit” button
on the interaction screen, and a “Play this interaction” button on the
edit screen.