Added self-update

Update.qml

@@ -0,0 +1,49 @@
+/* Copyright 2018 WobLight
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import QtQuick 2.9
+import GitAddonsManager.engine 1.0
+import QtQuick.Controls 2.4
+import QtQuick.Layouts 1.3
+
+ApplicationWindow {
+    visible: true
+    title: "Updating..."
+    width: errorDialog.visible?errorDialog.implicitWidth:bar.implicitWidth
+    height: errorDialog.visible?errorDialog.implicitHeight:bar.implicitHeight
+    flags: Qt.FramelessWindowHint
+    color: "transparent"
+    ProgressBar {
+        visible: Engine.status !== Engine.Error
+        id: bar
+        anchors.fill: parent
+        to: Engine.total
+        value: Engine.progress
+        indeterminate: to <= 0
+    }
+    Dialog {
+        id: errorDialog
+        visible: Engine.status === Engine.Error
+        standardButtons: Dialog.Close
+        onClosed: Qt.exit(-2)
+        title: qsTr("GitAddonsManager update error")
+        Label {
+            text: Engine.statusMessage
+        }
+    }
+
+    onClosing: {}
+}