use loop to create aliases for dir stack

If DIRSTACKSIZE is set, create alias for each stack entry.
if DIRSTACKSIZE is not set, create same as previous hard coded method.

lib/directories.zsh

@@ -9,16 +9,13 @@ alias -g .....='../../../..'
 alias -g ......='../../../../..'
 
 alias -- -='cd -'
-alias 1='cd -1'
-alias 2='cd -2'
-alias 3='cd -3'
-alias 4='cd -4'
-alias 5='cd -5'
-alias 6='cd -6'
-alias 7='cd -7'
-alias 8='cd -8'
-alias 9='cd -9'
 
+local n lim
+[[ -v DIRSTACKSIZE ]] && lim=$DIRSTACKSIZE || lim=9
+for n in {1..$lim}; do
+  alias $n="cd -$n"
+done
+  
 alias md='mkdir -p'
 alias rd=rmdir