Avoid HTML processing of image specifiers in link descriptions.

A link to an image can function as the description part of a link, to
create a clickable image.  The corresponding image tag was
erroneously processed like normal text.  This patch protects such
descriptions from processing.

Reported by Richard Riley.

lisp/ChangeLog

@@ -1,5 +1,10 @@
 2008-11-17  Carsten Dominik  <carsten.dominik@gmail.com>
 
+	* org-exp.el (org-export-html-format-desc): Respect the
+	org-protect property.
+	(org-export-as-html): Protect image specifiers that are in the
+	description part of a link.
+
 	* org.el (org-sort-entries-or-items, org-completing-read)
 	(org-refile-get-location, org-olpath-completing-read, org-todo)
 	(org-show-todo-tree, org-sparse-tree, org-make-tags-matcher)

lisp/org-exp.el

@@ -3245,7 +3245,9 @@ lang=\"%s\" xml:lang=\"%s\">
 	      (save-match-data
 		(if (string-match "^file:" desc)
 		    (setq desc (substring desc (match-end 0)))))
-	      (setq desc (concat "<img src=\"" desc "\"/>")))
+	      (setq desc (org-add-props
+			     (concat "<img src=\"" desc "\"/>")
+			     '(org-protected t))))
 	    ;; FIXME: do we need to unescape here somewhere?
 	    (cond
 	     ((equal type "internal")
@@ -3623,7 +3625,7 @@ lang=\"%s\" xml:lang=\"%s\">
 
 (defun org-export-html-format-desc (s)
   "Make sure the S is valid as a description in a link."
-  (if s
+  (if (and s (not (get-text-property 1 'org-protected s)))
       (save-match-data
 	(org-html-do-expand s))
     s))