While fixing a bug that log messages were ending up
in the output buffer for backups, we fixed up a bunch of
things to do with log messages and output for various
commands.
Due to a subtle oversight, this means that since we did
that, executor_test's `chkSumCluster` has been dutifully
printing `hash:blahblahblah` to os.Stdout, and returning
an empty string.
This also, indirectly, fixes a very strange behavior
we've had ever since then, which is that a lot of test
output silently disappears. The reason is probably,
although I haven't found the right code path, that we
were ending up closing os.Stdout.
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)
