Replaces the term 'element' with the term 'function' so that it's
clearer what we're talking about. (I'm aware that `element` is an SGML
term, but I think that the goal here is communication, rather than
necessarily using the right jargon.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1433780 13f79535-47bb-0310-9956-ffa450edef68