This commit completely switches us over to using a
dedicated model called MutedTopic to track which topics
a user has muted.
This includes the necessary migrations to create the
table and populate it from legacy data in UserProfile.
A subsequent commit will actually remove the old field
in UserProfile.
Most of the code in show_unreads is for diagnosising unread
counts issues, and we may not use that often.
We're creating a dedicated fix_unreads management command with
less clutter.
This now breaks the process of cleaning up unread counts for
non-active streams into a three step process.
This allows us to use our unread message flags index, at least
in testing on dev. Here is the relevant excerpt from explain
analyze:
Bitmap Index Scan on zerver_usermessage_unread_message_id
rht
Steve Howell
Steve Howell