Add configuration for zsh

- Add ~/.zshrc
  + Configure on how the `history` works
  + Enable nicer `cd` and globbing behavior
  + Enable tab completion, and make them feel nicer
  + Enable VI mode and add some VI-like key bindings
- Add ~/.zlogout clearing the screen
- Add ~/.config/zsh/.zshrc and make it dispatch to ~/.zshrc
  to make `zsh` use the same configuration even on more
  recent Debian/Ubuntu machines that do not look for
  ~/.zshrc any more
- Ensure ~/.local/state/zsh/ exists

.bashrc

@@ -64,6 +64,7 @@ if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
 fi
 
 
+# Align `bash` and `zsh` for prompts (see `$PS1` in ~/.zshrc)
 PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '