Virtual categories subtree

[julienanquetil]

According to the (old) RFS : #49

Automatic generation of a subtree for virtual categories when a root category is set.

As an Eshop manager, i want to be able to create a virtual category for "Pink products"
So i create a virtual category with "default category" as Root
And as condition i select attribute color with value Pink

I expect to see all my pink product on my virtual category on frontend with the layered navigation including categories in order to be able to filter on "top", "pants"...