Previously we used custom fields to denote a user was anonymous, this was
risky in that custom fields are prone to race conditions and are not
properly dedicated, missing constraints and so on.
The new table `anonymous_users` is properly protected. There is only one
possible shadow account per user, which is enforced using a constraint.
Every anonymous user will have a unique row in the new table.
This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
This allows users who entered a typo or invalid email address when
signing up an opportunity to fix it and resending the confirmation
email to that address.
Also changes behaviour of real to not return anonymous users.
This means user counts will no longer include them, and the
mailing list system will ignore them even if they somehow end up
with the feature turned on.
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.
