fix #678,provide a previewsDelay for latte plasmoid

--the user can add a previewsDelay value in ms in the
latte plasmoid General settings which can be found
in a layout file in order to change the delay which
a preview is needed to be activated. Values lower
than 150ms are ignored because they break the previews
experience by providing faulty previews

plasmoid/package/contents/config/main.xml

@@ -110,6 +110,10 @@
     <entry name="indicateAudioStreams" type="Bool">
       <default>true</default>
     </entry>
+    <entry name="previewsDelay" type="Int">
+      <label>Delay in order to show previews or highlight windows. Values lower than 150ms are ignored because previews do not work correctly</label>
+      <default>600</default>
+    </entry>
   </group>
 </kcfg>
 

plasmoid/package/contents/ui/task/TaskDelegate.qml

@@ -1250,7 +1250,7 @@ MouseArea{
         Timer {
             id: hoveredTimer
 
-            interval: 600
+            interval: Math.max(150,plasmoid.configuration.previewsDelay)
 
             repeat: false