Add \checkmark as a valid symbol

lisp/ChangeLog

@@ -1,5 +1,7 @@
 2010-01-08  Carsten Dominik  <carsten.dominik@gmail.com>
 
+	* org-exp.el (org-html-entities): Add checkmark symbol.
+
 	* org-ascii.el (org-export-ascii-preprocess): Protect targets in
 	verbatim code for ASCII export.
 

lisp/org-exp.el

@@ -1020,6 +1020,7 @@ value of `org-export-run-in-background'."
     ("aring")
     ("aelig")
     ("ccedil")
+    ("checkmark" . "✓")
     ("egrave")
     ("eacute")
     ("ecirc")