Infer nested entity names

[snusnu]

Given the following mapper definition, nested entity names like detailed_person.account and detailed_person.task should be inferred automatically.

register :detailed_person do
  map :id,   from: :person_id
  map :name, from: :person_name

  wrap :account, entity: :'detailed_person.account' do
    map :id,    from: :account_id
    map :email, from: :account_email
  end

  group :tasks, entity: :'detailed_person.task' do
    map :id,   from: :task_id
    map :name, from: :task_name
  end
end