extract: Reformat code

Signed-off-by: Kare Nuorteva <kare.nuorteva@me.com>
extract: Remove duplication

Signed-off-by: Kare Nuorteva <kare.nuorteva@me.com>
extract: Redirect error messages to STDERR

Signed-off-by: Kare Nuorteva <kare.nuorteva@me.com>
extract: Return error code on exit

Signed-off-by: Kare Nuorteva <kare.nuorteva@me.com>
Fix Zsh dotfiles comments text width

Signed-off-by: Kare Nuorteva <kare.nuorteva@me.com>