Fix markdown-cycle issue

Use own outline-show-entry implementation. Because outline-show-entry
uses only header regexp. So it misjudges header like statement, like
comment line of Ruby, in code block. This own implementation searches
header and whether there is in code block.

markdown-mode.el

@@ -1985,10 +1985,6 @@ in XEmacs 21."
     (if (fboundp 'outline-hide-body)
         'outline-hide-body
       'hide-body))
-  (defalias 'markdown-show-entry
-    (if (fboundp 'outline-show-entry)
-        'outline-show-entry
-      'show-entry))
   (defalias 'markdown-show-children
     (if (fboundp 'outline-show-children)
         'outline-show-children
@@ -4916,6 +4912,27 @@ For example, headings inside preformatted code blocks may match
 (defvar markdown-cycle-global-status 1)
 (defvar markdown-cycle-subtree-status nil)
 
+(defun markdown-next-preface ()
+  (let (finish)
+    (while (and (not finish) (re-search-forward (concat "\n\\(?:" outline-regexp "\\)")
+                                                nil 'move))
+      (unless (markdown-code-block-at-point)
+        (goto-char (match-beginning 0))
+        (setq finish t))))
+  (when (and (bolp) (or outline-blank-line (eobp)) (not (bobp)))
+    (forward-char -1)))
+
+(defun markdown-show-entry ()
+  (save-excursion
+    (outline-back-to-heading t)
+    (outline-flag-region (1- (point))
+                         (progn
+                           (markdown-next-preface)
+                           (if (= 1 (- (point-max) (point)))
+                               (point-max)
+                             (point)))
+                         nil)))
+
 (defun markdown-cycle (&optional arg)
   "Visibility cycling for Markdown mode.
 If ARG is t, perform global visibility cycling.  If the point is