Work around the lack of onValueModified signal in QQC 1

SpinBox in QtQuick Controls 2 has a signal that is emitted when the
value is changed explicitly by the user. In QtQuick Controls 1, there is
no such a signal.

The most straightforward thing would be to switch to QQC2, but the
problem is that the SpinBox API in there is extremely stripped down. You
will need to re-invent the wheel to get basic functionality.

This fixes a bug where the update interval is reset to 1 unexpectedly.

src/package/contents/ui/config.qml

@@ -115,13 +115,20 @@ ColumnLayout {
         }
 
         QtControls.SpinBox {
+            property bool __initialized: false
             id: updateIntervalSpinBox
             Kirigami.FormData.label: i18nd("plasma_wallpaper_com.github.zzag.dynamic", "Update Every:")
             maximumValue: 360
             minimumValue: 1
             suffix: i18ndp("plasma_wallpaper_com.github.zzag.dynamic", " minute", " minutes", value)
-            onValueChanged: cfg_UpdateInterval = value * 60000
-            Component.onCompleted: value = wallpaper.configuration.UpdateInterval / 60000
+            onValueChanged: {
+                if (__initialized)
+                    cfg_UpdateInterval = value * 60000;
+            }
+            Component.onCompleted: {
+                value = cfg_UpdateInterval / 60000;
+                __initialized = true;
+            }
         }
     }