Yellow highlight in QML CollectionView component.

The delegate's background is forced to be transparent if current item.
The highlight is a light yellow rectangle. The horizontal separator
before the current item is set to a darker yellow color (shadow).
When the model emits the "modelReset“ signal, we set the view's current
index to -1. Add active focus trough mouse click in the Collection
component. Not sure if this is done right. Would be nice to have a nice
focus chain on <tab>.
Add property “total“ to CollectionModel.

The “total“ property is changed when the model is about intialized. In
the CollectionView component, the “keyNavigationWraps“ is enabled only
when the model size is equal the total size (to allow wrapping only when
the model is completly loaded).
Add support for keyboard navigation in Collection.

You can use <left>, <right>, <tab> and <backtab> to jump between the
filter view and the collection view.