Revert "Fix :VISIBILITY: handling of nested "folded" properties"

This reverts commit 383802d063a9f2dd959d5574b226fa8ec7f8be41.

The commit had org-mode process the headlines from bottom to top, which
meant that any changes to the visibility of lower headlines were
overridden/modified by changes higher up the tree. Reverting the commit
causes VISIBILITY to work correctly.

lisp/org.el

@@ -6076,8 +6076,8 @@ With a numeric prefix, show all headlines up to that level."
   (interactive)
   (let (org-show-entry-below state)
     (save-excursion
-      (goto-char (point-max))
-      (while (re-search-backward
+      (goto-char (point-min))
+      (while (re-search-forward
 	      "^[ \t]*:VISIBILITY:[ \t]+\\([a-z]+\\)"
 	      nil t)
 	(setq state (match-string 1))