Merge branch '2.3-stable' into msu-2.3

Conflicts:
	Gemfile
	app/controllers/wiki_controller.rb
	app/models/mail_handler.rb
	app/models/principal.rb
	app/views/issues/_list.html.erb
	app/views/queries/_filters.html.erb
	config/locales/de.yml
	config/locales/ja.yml
	config/locales/nl.yml
	config/locales/ru.yml
	config/locales/zh-TW.yml
	config/locales/zh.yml
	doc/CHANGELOG
	doc/INSTALL
	lib/SVG/Graph/TimeSeries.rb
	lib/redmine/version.rb
	public/javascripts/application.js
	test/functional/issues_controller_test.rb
	test/unit/helpers/application_helper_test.rb
	test/unit/helpers/issues_helper_test.rb
	test/unit/issue_test.rb
	test/unit/project_nested_set_test.rb
	test/unit/version_test.rb