Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- .github/ISSUE_TEMPLATE/bug_report.md
  Took our version.
- CONTRIBUTING.md
  Updated the embedded copy of upstream's version.
- README.md
  Took our version.
- app/policies/status_policy.rb
  Not a real conflict, took code from both.
- app/views/layouts/embedded.html.haml
  Added upstream's changes (dns-prefetch) and fixed
  `%body.embed`
- app/views/settings/preferences/show.html.haml
  Reverted some of upstream changes, as we have a
  page dedicated for flavours and skins.
- config/initializers/content_security_policy.rb
  Kept our version of the CSP.
- config/initializers/doorkeeper.rb
  Not a real conflict, took code from both.

app/models/status.rb

@@ -39,7 +39,7 @@ class Status < ApplicationRecord
 
   update_index('statuses#status', :proper) if Chewy.enabled?
 
-  enum visibility: [:public, :unlisted, :private, :direct], _suffix: :visibility
+  enum visibility: [:public, :unlisted, :private, :direct, :limited], _suffix: :visibility
 
   belongs_to :application, class_name: 'Doorkeeper::Application', optional: true
 
@@ -54,7 +54,8 @@ class Status < ApplicationRecord
   has_many :bookmarks, inverse_of: :status, dependent: :destroy
   has_many :reblogs, foreign_key: 'reblog_of_id', class_name: 'Status', inverse_of: :reblog, dependent: :destroy
   has_many :replies, foreign_key: 'in_reply_to_id', class_name: 'Status', inverse_of: :thread
-  has_many :mentions, dependent: :destroy
+  has_many :mentions, dependent: :destroy, inverse_of: :status
+  has_many :active_mentions, -> { active }, class_name: 'Mention', inverse_of: :status
   has_many :media_attachments, dependent: :nullify
 
   has_and_belongs_to_many :tags
@@ -94,7 +95,7 @@ class Status < ApplicationRecord
                    :status_stat,
                    :tags,
                    :stream_entry,
-                   mentions: :account,
+                   active_mentions: :account,
                    reblog: [
                      :account,
                      :application,
@@ -103,7 +104,7 @@ class Status < ApplicationRecord
                      :media_attachments,
                      :conversation,
                      :status_stat,
-                     mentions: :account,
+                     active_mentions: :account,
                    ],
                    thread: :account
 
@@ -176,7 +177,11 @@ class Status < ApplicationRecord
   end
 
   def hidden?
-    private_visibility? || direct_visibility?
+    private_visibility? || direct_visibility? || limited_visibility?
+  end
+
+  def distributable?
+    public_visibility? || unlisted_visibility?
   end
 
   def with_media?
@@ -240,6 +245,10 @@ class Status < ApplicationRecord
       left_outer_joins(:status_stat).select('statuses.id, greatest(statuses.updated_at, status_stats.updated_at) AS updated_at')
     end
 
+    def selectable_visibilities
+      visibilities.keys - %w(direct limited)
+    end
+
     def in_chosen_languages(account)
       where(language: nil).or where(language: account.chosen_languages)
     end