qt: daemon now operates in the background thread; added Quit GUI button

qt/i2pd_qt/mainwindow.h

@@ -2,6 +2,16 @@
 #define MAINWINDOW_H
 
 #include <QMainWindow>
+#include <QPushButton>
+#include <QtCore/QVariant>
+#include <QtWidgets/QAction>
+#include <QtWidgets/QApplication>
+#include <QtWidgets/QButtonGroup>
+#include <QtWidgets/QHeaderView>
+#include <QtWidgets/QMainWindow>
+#include <QtWidgets/QPushButton>
+#include <QtWidgets/QVBoxLayout>
+#include <QtWidgets/QWidget>
 
 namespace Ui {
 class MainWindow;
@@ -15,8 +25,14 @@ public:
     explicit MainWindow(QWidget *parent = 0);
     ~MainWindow();
 
+private slots:
+    void handleQuitButton();
+
 private:
-    Ui::MainWindow *ui;
+    QWidget *centralWidget;
+    QWidget *verticalLayoutWidget;
+    QVBoxLayout *verticalLayout1;
+    QPushButton *quitButton;
 };
 
 #endif // MAINWINDOW_H