WebStyle: avoid double-escaping title in page header

• Changed websearch_templates.tmpl_record_page_header_content() to not return escaped output. Escape title/description/keyword only when needed. Changed webstyle.tmpl_pageheader() to escape quotes in description/keywords.

• Clarified usage of some functions wrt escaping of input parameters and returned output.

• If you have modified webstyle_templates.tmpl_pageheader() function, ensure that you use 'cgi.escape(description, True)' and 'cgi.escape(keywords, True)' when preparing for description and keyword header tag.

• If you have modified websearch_templates.tmpl_record_page_header_content() function, make sure that you do not return escaped output.