commit instead of cancel for win; closes #8

src/pcsc.hxx

@@ -180,7 +180,10 @@ namespace pcsc {
               [...]
               t.commit(); // commit if we reach this line
               } // cancelled, unless commit reaced
-              @endcode */
+              @endcode
+
+              @note Micro$oft QinSCard does not know cancel, therefore
+              on Windoze cancel is replaced by commit. */
           class Transaction {
             public:
               //! Begins a transaction.
@@ -356,8 +359,15 @@ namespace pcsc {
           }
 
           //! Use scoped transactions with @ref Transaction
+          /*! @note Micro$oft QinSCard does not know cancel, therefore
+              on Windoze cancel is replaced by commit. */
           void cancelTransaction() {
+#ifdef WIN32
+            check(SCardEndTransaction(_id, SCARD_LEAVE_CARD),
+                  "smartcard end transaction");
+#else
             check(SCardCancelTransaction(_id), "smartcard cancel transaction");
+#endif
           }
 
           /*! @throw not_implemented if _protocol is unknown. */