This CL mostly deletes code.

Using existing position information is
just as good to determine if a new section
is needed; no need to track exact multi-
line information. Eliminates the need to
carry around a multiLine parameter with
practically every function.

Applied gofmt -w src misc resulting in only
a minor change to godoc.go. In return, a couple
of test cases are now formatted better.

Not Go1-required, but nice-to-have as it will
simplify fixes going forward.

R=rsc
CC=golang-dev
https://golang.org/cl/5706055