Guoxue Dashi calligraphy search por Philipp Immel

The search engine addon can currently only use the mobile version of the Guoxue Dashi search, because `search_provider.search_url` MUST be a HTTPS URL but Guoxue Dashi’s SSL certificate is only valid for the m2.guoxuedashi.com domain and not for www.guoxuedashi.com.