Size "Do you want to use saved settings?" dialog box better

Prevents buttons overflowing the dialog box when German language
translation is used.
(Issue reported on forum)

src/UseSavedSettingsPopup.qml

@@ -11,9 +11,9 @@ import "qmlcomponents"
 
 Popup {
     id: msgpopup
-    x: 75
+    x: (parent.width-width)/2
     y: (parent.height-height)/2
-    width: parent.width-150
+    width: Math.max(buttons.width+10, parent.width-150)
     height: msgpopupbody.implicitHeight+150
     padding: 0
     closePolicy: Popup.CloseOnEscape | Popup.CloseOnPressOutside
@@ -91,6 +91,7 @@ Popup {
             Layout.alignment: Qt.AlignCenter | Qt.AlignBottom
             Layout.bottomMargin: 10
             spacing: 20
+            id: buttons
 
             ImButton {
                 text: qsTr("NO")