Overshoot should follow rough heuristic

Change-Id: I231812944a645e120b80af18dde2ab18d2addd6a

Gravity.qml

@@ -39,7 +39,7 @@ Item {
             property int columnHeight: 0
 
             function addImage() {
-                if (columnHeight < settings.columnBufferFactor*root.height) {
+                if (columnHeight < (1.1+1/settings.columnCount)*root.height) {
                     var item = pictureDelegate.createObject(column)
                     columnHeight += item.height
                     item.y = (floor.y - 1) - columnHeight

main.qml

@@ -16,7 +16,6 @@ Window {
         property int interval: 30
         property bool fitByHeight: false
         property double pace: 1.0
-        property double columnBufferFactor: 1.2
         property bool viewItemCount: false
     }