Swirls is a much groovier/less invasive default background

Change-Id: Ic1c352554ef3fc5c6b80420c7cad2496b2d76327

qml/main.qml

@@ -88,7 +88,7 @@ Item {
 
         property string effect: ""
         property string artView: "Trivial"
-        property string backdrop: "Cells"
+        property string backdrop: "Swirls"
 
         property bool smoothArt: false
         property bool randomlyMirrorArt: false