Fix most rubocop issues (#2165)

* Run rubocop --autocorrect on app/, config/ and lib/, also manually fix some remaining style issues

* Run rubocop --autocorrect-all on db/

* Run rubocop --autocorrect-all on `spec/` and fix remaining issues

app/models/direct_feed.rb

@@ -4,9 +4,8 @@ class DirectFeed < Feed
   include Redisable
 
   def initialize(account)
-    @type    = :direct
-    @id      = account.id
     @account = account
+    super(:direct, account.id)
   end
 
   def get(limit, max_id = nil, since_id = nil, min_id = nil)
@@ -19,10 +18,12 @@ class DirectFeed < Feed
 
   private
 
-  def from_database(limit, max_id, since_id, min_id)
+  # TODO: _min_id is not actually handled by `as_direct_timeline`
+  def from_database(limit, max_id, since_id, _min_id)
     loop do
-      statuses = Status.as_direct_timeline(@account, limit, max_id, since_id, min_id)
+      statuses = Status.as_direct_timeline(@account, limit, max_id, since_id)
       return statuses if statuses.empty?
+
       max_id = statuses.last.id
       statuses = statuses.reject { |status| FeedManager.instance.filter?(:direct, status, @account) }
       return statuses unless statuses.empty?