Add frequent-directory function

`frequent-directory` exports and environment variable and creates a hash
directory with the given argument of the form `<name>=<path>`.

zshrc

@@ -173,6 +173,10 @@ if [[ ! -z "$cursor_block" && ! -z "$cursor_line" ]]; then
   zle -N zle-line-finish
 fi
 
+# Frequntly used directories
+function frequent-directory() { export $1; hash -d $1 }
+frequent-directory Projects="$HOME/Projects"
+
 # Load work related config
 [ -f ~/.config/work/zshrc ] && source ~/.config/work/zshrc
 
@@ -205,6 +209,3 @@ case `uname` in
       alias debug='lldb --'
     ;;
 esac
-
-# Hashed Directories
-hash -d Projects="$HOME/Projects"