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

.config/shell/aliases

@@ -12,9 +12,19 @@ forget() {  # the current history and restore $HISTFILE from disk
     if [ -n "$BASH_VERSION" ]; then
         history -c
         history -r
+    elif [ -n "$ZSH_VERSION" ]; then
+        local _histsize=$HISTSIZE
+        HISTSIZE=0  # because shrinking the list to 0 discards all entries
+        HISTSIZE=$_histsize
+        fc -R "$HISTFILE"
     fi
 }
 
+if [ -n "$ZSH_VERSION" ]; then
+    alias forget=' forget'  # Leading space => The invocation itself is forgotten
+fi
+
 
 
 alias grep='grep --exclude-dir=.git'
+