This is causing issues when purging old users, if they are set up in the
exact condition where they will be demoted into another group, but also
do not have a primary email.
* PERF: Dematerialize topic_reply_count
It's only ever used for trust level promotions that run daily, or compared to 0. We don't need to track it on every post creation.
* UX: Add symbol in TL3 report if topic reply count is capped
* DEV: Drop user_stats.topic_reply_count column
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
Changed internals so trust levels are referred to with
TrustLevel[1], TrustLevel[2] etc.
This gives us much better flexibility naming trust levels, these names
are meant to be controlled by various communities.
Introduced badge triggers, introduced concept of badge that happens due to a post but has the post hidden
Delta badge grant happens once a minute, backed by redis
* rename `User#password_required` to `User#password_required!`
* emails with "i" @ something are a special case as well
* get rid of `self.` and returns where possible
* prefer "unless a" instead of "if !a"
* `unread_notifications` without manually iterating
* introduce `User#moderator?`
* introduce `TrustLevel#valid_key?`, `TrustLevel#compare`, and
`TrustLevel#level_key`