revision plan for the /bboard system

• we switch from a varchar primary key to an integer (part of a general ACS-wide move to simple integer primary keys); retaining the old sort_key system, though, and also preserving the legacy keys in a separate column so that people can still point to threads
• let's increase the number of chars used at any one level to 4 (from 2). This will address the needs of sites like cnn.com where they don't use threading and have a gazillion responses to the same top-level question
• we have soft-delete by the moderators (thread disappears from the moderated version but is still in the database) and a mode where new questions require approval before they go live in the moderated version ("don't show this to anyone until at least one moderator has said it was okay")
• we use the abstract URL system
• (to support the edu module and MIT Sloan School) scoping of bboards by roles within a group (so that a bboard can be for professors and TAs in a class but not students)
• (related to above) make sure that the bboard system works with the group scoping stuff (subcommunities)
• some additional abstraction in the database at the PL/SQL level, e.g., a function that answers the question "Can User 17 read Bboard Topic #32?"
• a more sensible approach to this "featured", unmoderated, etc. stuff (template it!) on the home page (and don't show people bboards in which they are prohibited from reading))
• an actually useful threaded interface for bboards with 100,000 postings
• maybe some abstraction out of the USgeospatial stuff (we should be able to tie discussions to arbitrary other objects in the database, using on_which_table, on_what_id style of pointing)

Email Fixes

• take out the control-Ms
• From header should say "Joe Smith via photo.net bboard <joes@foobar.com>"
• the email notifications should have a link not just to the overall bboard but to the individual thread
• correctly set References: and In-Reply-To: headers so that a mail reader can display these as threads
• (hard and make it configurable) inbound email gets posted to the bboard in the right place

Bug Fixes

• the Q&A admin pages should not warn you that a user has turned off notification when in fact there is a thread alert