Start to implement module-defined hooks that are a) fast and b) typesafe.

Replace pre_connection module call with a register_hook call and
implement pre_connection as a hook. The intent is that these hooks will
be extended to allow Apache to be multi-protocol, and also to allow the
calling order to be specified on a per-hook/per-module basis.  [Ben Laurie]

Port a bunch of modules to the new module structure.
["Michael H. Voase" <mvoase@midcoast.com.au>]

Submitted by:   Ben Laurie


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@83786 13f79535-47bb-0310-9956-ffa450edef68