add BNP flag to give control to the user on whether a space ' ' in

an escaped backrefernece is decoded to a + (default) or %20. Useful
if your backreference isn't going into the query string.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1585157 13f79535-47bb-0310-9956-ffa450edef68