several small Qt-related fixes

- make BitcoinGUI::showPaymentACK() use a reference for msg and use our
  own GUIUtil::HtmlEscape() function
- ensure QTimer usage in clientmodel is the same as in walletmodel
- remove an unneeded debug message in walletframe
- flag some parameters as unused in DebugMessageHandler()
- small code formatting changes

src/qt/bitcoin.cpp

@@ -155,11 +155,14 @@ static void initTranslations(QTranslator &qtTranslatorBase, QTranslator &qtTrans
 #if QT_VERSION < 0x050000
 void DebugMessageHandler(QtMsgType type, const char * msg)
 {
+    Q_UNUSED(type);
     LogPrint("qt", "Bitcoin-Qt: %s\n", msg);
 }
 #else
 void DebugMessageHandler(QtMsgType type, const QMessageLogContext& context, const QString &msg)
 {
+    Q_UNUSED(type);
+    Q_UNUSED(context);
     LogPrint("qt", "Bitcoin-Qt: %s\n", qPrintable(msg));
 }
 #endif

src/qt/bitcoingui.cpp

@@ -751,13 +751,9 @@ void BitcoinGUI::handlePaymentRequest(const SendCoinsRecipient& recipient)
     walletFrame->handlePaymentRequest(recipient);
 }
 
-void BitcoinGUI::showPaymentACK(QString msg)
+void BitcoinGUI::showPaymentACK(const QString& msg)
 {
-#if QT_VERSION < 0x050000
-    message(tr("Payment acknowledged"), Qt::escape(msg), CClientUIInterface::MODAL);
-#else
-    message(tr("Payment acknowledged"), msg.toHtmlEscaped(), CClientUIInterface::MODAL);
-#endif
+    message(tr("Payment acknowledged"), GUIUtil::HtmlEscape(msg), CClientUIInterface::MODAL);
 }
 
 void BitcoinGUI::setEncryptionStatus(int status)

src/qt/bitcoingui.h

@@ -154,7 +154,7 @@ public slots:
     void askFee(qint64 nFeeRequired, bool *payFee);
 
     void handlePaymentRequest(const SendCoinsRecipient& recipient);
-    void showPaymentACK(QString msg);
+    void showPaymentACK(const QString& msg);
 
     /** Show incoming transaction notification for new transactions. */
     void incomingTransaction(const QString& date, int unit, qint64 amount, const QString& type, const QString& address);

src/qt/clientmodel.cpp

@@ -24,9 +24,8 @@ ClientModel::ClientModel(OptionsModel *optionsModel, QObject *parent) :
     numBlocksAtStartup(-1), pollTimer(0)
 {
     pollTimer = new QTimer(this);
-    pollTimer->setInterval(MODEL_UPDATE_DELAY);
-    pollTimer->start();
     connect(pollTimer, SIGNAL(timeout()), this, SLOT(updateTimer()));
+    pollTimer->start(MODEL_UPDATE_DELAY);
 
     subscribeToCoreSignals();
 }