Remove multiple and defaultData in the next major version

[klis87]

I don't want to keep it, especially defaultData as it makes getQuery more complex than it has to be. It doesn't really do too much anyway, people can always provide a fallback for null on the app level. Another reason to remove it is to simplify API when it is possible, as we support more and more features, the API grows, so to balance it, we should remove what we can.

Please provide reasons if you don't like this plan.