Gachi - cascade deletes implemented

I've written a roadmap for Gachi and one of the biggest steps was to implement cascade deletes and it's DONE! (as in working :-) )

Since Google App Engine's datastore is kinda hierarchical but then not really, you have to delete all child entities yourself, when you delete the "parent" entity. I'm really pleased with my implementation where I've introduced a meta-info concept where I, when deleting an entity, knows which child entities I must also delete.

Next up - Query interface