* Add (commented out) linters that we should introduce
I went through the available linters and added (commented out) the ones
I think we should work on in the near term. In other words, fix them,
then uncomment them so they are enabled in CI.
* linter: errchkjson
* linter: ineffassign
* linter: gosimple
* linter: errname
stdout/stderr around
A lot of functions in the cmd and ctl packages were passing these
around and barely using them. Replaced them with a logger for most
functions. Some functions get an io.Writer instead so that their
tests can find the output they're looking for.
More cleanup on fb-1766: reworked the tests that were using io.Pipe
or os.Pipe to check their results so they now use a bytes.Buffer.
Unexported some variables that didn't need to be exported.
Fixed NewConfigCommand to use the provided stderr, not os.Stderr.
Added tests for rbf_dump, rbf_page, and keygen, since those weren't
being tested at all.
Added chksum_test, final cleanup.
(cherry picked from commit f627199acb)
