Revert "Revert "split help.jl & i18n.jl out of util.jl""

This reverts commit d1a18a78db3c6d0a2326c22fafda1aee32e7775f.
Merge branch 'master' into vs/util
Merge pull request #2595 from JuliaLang/vs/util

WIP: util.jl refactor crashes mac