不是用QStringRef，太容易出错。

Signed-off-by: facat@lab.com <facat@lab.com>

testHasttable/synchronousmachine.h

@@ -5,10 +5,10 @@
 class SynchronousMachine:public BasicElementInfo
 {
 public:
-    SynchronousMachine();
+    explicit SynchronousMachine(QObject *parent = 0);
     virtual bool parse(QXmlStreamReader& reader);
 protected:
-    QStringRef terminal;
+    QString terminal;
     virtual bool derivedParse(QXmlStreamReader& reader);
 };