fix macro expansion with separators and backslashes

* lisp/org-macro.el (org-macro-expand): Do not try to interpret the
  macro replacement text as a regex so that escaped backslashes and
  commas in macro arguments will be interpreted correctly.

lisp/org-macro.el

@@ -144,7 +144,7 @@ default value.  Return nil if no template was found."
                                (org-element-property :args macro))
                           ;; No argument: remove place-holder.
                           ""))
-                    template)))
+                    template nil 'literal)))
         ;; VALUE starts with "(eval": it is a s-exp, `eval' it.
         (when (string-match "\\`(eval\\>" value)
           (setq value (eval (read value))))