Major change to how okd handles dispatching client connections to web
server processes. The changes are the following:

* Instead of just reading and parsing the request line, okd now reads
  all the request headers.
* It sends the headers along to find_best_fit_child() so it can use the
  X-Forwarded-For header (or equivalents) to determine which child
  to send to.
* Add new options ChildMode=2, and OkdAllHeaders to control this new
  behavior.