ThemesHelper reopening ApplicationHelper is problem with autoloading (#20507).

Patch by Ondřej Ezr.

git-svn-id: http://svn.redmine.org/redmine/trunk@14511 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/redmine/themes.rb

@@ -126,7 +126,7 @@ module Redmine
   end
 end
 
-module ApplicationHelper
+module ThemesHelper
   def current_theme
     unless instance_variable_defined?(:@current_theme)
       @current_theme = Redmine::Themes.theme(Setting.ui_theme)
@@ -141,3 +141,4 @@ module ApplicationHelper
     end
   end
 end
+ActionView::Base.send(:include, ThemesHelper)