Allow for JIT configuration of necessary parents

[ludamillion]

The current mode of configuration makes adding DataWorks to an existing application (especially a very large one) a onerous task.

If DataWorks allowed for setting the necessary parents on an ad hoc basis it could be used on a spec by spec basis and eased into a testing suite over time. Or, could allow for it to only be used when needed.

Given the way that necessary parents are set (passing a data structure to the Config object) there infrastructure itself is probably usable for such purpose. I think what needs to be changed is the way in which it checks/blocks usage when there are missing entries in the necessary parents register.