add a new button to send contact request, some ui tweaks

src/mainwindow.h

@@ -92,10 +92,14 @@ public slots:
     void slot_change_currency(const QString& currencyName);
     
      
-private:    
+private slots:
+    
+
+private:
 
     void closeEvent(QCloseEvent* event);
 
+
     void setupSendTab();
     void setupTransactionsTab();
     void setupReceiveTab();