sitemap revision: support for new sitemap.xml

new sitemap.dtd and sitemap.xsl
added some corresponding items to en.xml
added new li.separate style to manual.css

also, increased the distance between list items inside the sidebar


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96729 13f79535-47bb-0310-9956-ffa450edef68