drop settings_compatible which was used for Redmine 3.x compatiblitiy, fix coding standards for rubocop update

.rubocop.yml

@@ -70,3 +70,6 @@ Style/HashTransformKeys:
 
 Style/HashTransformValues:
   Enabled: false
+
+Naming/VariableNumber:
+  Enabled: false

app/models/additionals_query.rb

@@ -106,23 +106,19 @@ module AdditionalsQuery
   end
 
   def initialize_author_filter(options = {})
-    return if author_values.empty?
-
     add_available_filter('author_id', order: options[:position],
                                       type: :list_optional,
                                       values: options[:no_lambda].nil? ? author_values : -> { author_values })
   end
 
   def initialize_assignee_filter(options = {})
-    return if author_values.empty?
-
     add_available_filter('assigned_to_id', order: options[:position],
                                            type: :list_optional,
                                            values: options[:no_lambda] ? assigned_to_all_values : -> { assigned_to_all_values })
   end
 
   def initialize_watcher_filter(options = {})
-    return if watcher_values.empty? || !User.current.logged?
+    return unless User.current.logged?
 
     add_available_filter('watcher_id', order: options[:position],
                                        type: :list,

lib/additionals.rb

@@ -66,18 +66,6 @@ module Additionals
                      recently_updated reddit slideshare tradingview twitter user vimeo youtube asciinema]
     end
 
-    def settings_compatible(plugin_name)
-      if Setting[plugin_name].is_a? Hash
-        # convert Rails 4 data (this runs only once)
-        new_settings = ActiveSupport::HashWithIndifferentAccess.new Setting[plugin_name]
-        Setting.send "#{plugin_name}=", new_settings
-        new_settings
-      else
-        # Rails 5 uses ActiveSupport::HashWithIndifferentAccess
-        Setting[plugin_name]
-      end
-    end
-
     # support with default setting as fall back
     def setting(value)
       if settings.key? value
@@ -161,7 +149,7 @@ module Additionals
     private
 
     def settings
-      settings_compatible :plugin_additionals
+      Setting[:plugin_additionals]
     end
   end
 end