- Fix bugs 1491, 1653 (on PG at least)
- Defaults all folders to the closed state
- Fix to allow un-registered users to open/close folders
- Makes session_id negative when used interchangeably with user_id so it does
not collide with user_id
- The number of days to retain open/closed folder status is now a variable
(increased default from 1 to 31 days)