Reimplement mod_headers as an output filter. mod_headers can now

add custom headers to inbound requests using the HeaderIn directive
and to responses using the HeaderOut directive. The Header
directive has been deprecated in favor of the HeaderOut directive.

Submitted by: Graham Leggett
Reviewed by: Bill Stoddard


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89165 13f79535-47bb-0310-9956-ffa450edef68