Specify binary mode when reopening card file

include/kabufuda/Card.hpp

@@ -524,6 +524,11 @@ public:
      */
     void close();
 
+    /**
+     * @brief Access host filename of card
+     */
+    const SystemString& cardFilename() const { return m_filename; }
+
     /**
      * @brief Gets card-scope error state
      * @return READY, BROKEN, or NOCARD