CGI handling, including bin/40355 . There are two main changes here:
1) call process_cgi() after transform_request(), not before. Now it is
possible to have a default cgi handler catch a request for a path that
was produced by transformation, e.g. by index generation -- so now the
index can be "generated" by a CGI if that is what the user desires.
2) More clearly distinguish "file" from "query" portions of the request
URL, so we do not feed ?-suffixed "arguments" to plain files, fail to
match filename extensions due to ?-suffixes, etc.
After this change, there are only two cases which use the "query"
portion of the request (the portion after the ?):
a) A redirect issued by HTTPD will redirect to the new file, but
with the same query string.
b) process_cgi() will, of course continue to use the query string.
