Connection manager can now open a query window for selected connection.

Query window has now buttons with icons made in the designer for better looks.
Depending on received responses from the database the tabcontrol with the message, data and explain tab
now switches to the appropriate tab.

connectionmanagerwindow.h

@@ -25,6 +25,10 @@ private slots:
 	void on_currentChanged(const QModelIndex &current, const QModelIndex &previous);
 	void on_actionDelete_connection_triggered();
 
+	void on_actionConnect_triggered();
+
+	void on_actionQuit_application_triggered();
+
 private:
 	Ui::ConnectionManagerWindow *ui;
 	ConnectionListModel *m_listModel = nullptr;