tart getting things setup for input filtering. All this basically does

is add part of the infrastructure.  Namely:

1) filter list in the conn_rec, which is where the input filter list
   must live

2) Split the register_filter into multiple functions, one to register
   input filters the other to register output filters.

3) Modify existing modules so they still work.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@86251 13f79535-47bb-0310-9956-ffa450edef68