Arrange the code so that it's easier to keep edits in sync.
R=golang-dev, mikioh.mikioh, bradfitz, andybalholm, rsc
CC=golang-dev
https://golang.org/cl/5345041
This moves DumpRequest, DumpResponse, NewChunkedReader,
and NewChunkedWriter out of http, as part of the continued
http diet plan.
Also, adds DumpRequestOut (for dumping outbound requests),
since DumpRequest's ambiguity (the "wire representation" in
what direction?) was often a source of confusion and bug
reports.
R=rsc, adg
CC=golang-dev
https://golang.org/cl/5339041
Part of http diet plan.
More of the lesser-used and newcomer-misleading parts of http will
move here.
R=r, rsc
CC=golang-dev
https://golang.org/cl/5336049