Changes to DrProject's Ticketing System

Here’s a draft proposal for modifying DrProject’s ticketing system based on feedback from the post-mortem:

1. State is simply "open" or "closed", and becomes implicit: the buttons to update a ticket are labeled "Preview", "Update", and "Close".
2. Tickets can be assigned to roles, as well as to specific users, so that if an organization distinguishes "tester" from "developer", tickets can be marked accordingly.
3. Get rid of "type": if people want to distinguish different kinds of tickets, they can evolve a set of tags. (This is the same argument we used to get rid of the "component" field inherited from Trac.)

Still unsure what to do about actual and estimated effort: companies want it, but we know that student teams won’t use it (or that if they do, their numbers will be science fiction). Is a “small/medium/large” pulldown when filing the ticket enough, if people can adjust it again when closing the ticket to show actual effort?