Added start blocke on no database connection available

Gui/NoDbConnection.qml

@@ -0,0 +1,74 @@
+import QtQuick
+import QtQuick.Controls
+
+Rectangle
+{
+    anchors.fill: parent
+    color: "slateblue"
+
+    Rectangle
+    {
+        id: info
+        anchors.horizontalCenter: parent.horizontalCenter
+        color: "slateblue"
+        implicitHeight: 55
+        implicitWidth: parent.width / 4
+        y: parent.height / 4
+        Text
+        {
+            anchors.centerIn: parent
+            text: qsTr("Keine Verbindung zur Datenbank!")
+            color: "moccasin"
+            font.bold: true
+            font.pixelSize: 45
+        }
+    }
+
+    Rectangle
+    {
+        id: nostart
+        anchors.top: info.bottom
+        color: "slateblue"
+        anchors.horizontalCenter: parent.horizontalCenter
+        implicitHeight: 55
+        implicitWidth: parent.width / 4
+        Text
+        {
+            text: qsTr("Programm kann nicht starten..")
+            color: "moccasin"
+            anchors.centerIn: parent
+            font.bold: true
+            font.pixelSize: 45
+        }
+    }
+
+    Rectangle
+    {
+        anchors.top: nostart.bottom
+        anchors.topMargin: 25
+        anchors.horizontalCenter: parent.horizontalCenter
+        color: "slateblue"
+        implicitHeight: 55
+        implicitWidth: parent.width / 4
+        Button
+        {
+            width: parent.width
+            height: 75
+            Text
+            {
+                text: qsTr("Beenden")
+                color: "moccasin"
+                anchors.centerIn: parent
+                font.bold: true
+                font.pixelSize: 45
+            }
+            anchors.centerIn: parent
+            background: Rectangle
+            {
+                color: "dodgerblue"
+                radius: 50
+            }
+            onClicked: Qt.quit()
+        }
+    }
+}