Add Deepcopy feature.

[xnuinside]

Logic:

Copy chosen element and all data that depend on it in chain.

For example,
exist table user
exist table restaurants
exist table dishes
exist table drinks

user.id ForeignKey for Place as owner_id

user (one) to (many) Places

Place (one) to (many) dishes & drinks

So when we do 'Deepcopy' of 'user'

We copy all his Places, with all dishes and drinks that chained to Place