Make document builder an extension

[jasonkuhrt]

Perceived Problem

Make core leaner

Ideas / Proposed Solution(s)

Make generated interface an extension.

Need to think about core, which hard codes the concept of a raw versus typed interface.

It would require the core anyways data types to be extensible which is currently not possible. Also, it would require not just added types but removed types of raw.

In effect we would need to introduce an extensible interface concept. Might not be so bad/hard.