Port more Read-related code to reldb.
New duplicate aware abstract model, with much cleaner replace_duplicate() implementation.
New abstract tagged model implementation, with an already-complete and hopefully future-proof replace tag duplicate implementation.
Fix the Read MRO crash.
Oops. Make the task a task.
Reads and Subscriptions in the admin (prettier, I mean).
version bump for 0.80.
Merge branch 'release/0.80' into develop