* mu-msg: add support for GSList* fields

src/mu-msg.h

@@ -264,6 +264,16 @@ size_t          mu_msg_get_size       (MuMsg *msg);
 const char*  mu_msg_get_field_string  (MuMsg *msg, MuMsgFieldId mfid);
 
 
+/**
+ * get some field value as string-list
+ * 
+ * @param msg a valid MuMsg instance
+ * @param field the field to retrieve; it must be a string-list-typed field
+ * 
+ * @return a list that should not be freed
+ */
+const GSList* mu_msg_get_field_string_list (MuMsg *self, MuMsgFieldId mfid);
+
 /**
  * get some field value as string
  *