Merge r1524192, r1524770, r1527925 from trunk:

Update rationale


draft-ietf-httpbis-p1-messaging-23 fixes regarding interactions
between TE and content-length in the same req/resp.

PR 55616 (add missing APLOGNO), part 1
Reviewed by: rpluem, ylavic, wrowe


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1576708 13f79535-47bb-0310-9956-ffa450edef68