Cleanup

Rename variables, improve comments, etc, for clarity and to better fit
my programmerly preferences.
comments
Merge branch 'master' into cleanup
Merge branch 'master' into cleanup
Merge branch 'cleanup' of github.com:rupa/z into cleanup
redirect to dev/null a bit more POSIXly
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  redirect to dev/null a bit more POSIXly
  comments
  Cleanup