a359146: Add initial functionality for composition of subschemas, i.e. stitching.

This functionality will supplant object extension.

a359146: Change main export to transform from transformResult.

Instead of processing an existing result, the function delegates the request directly to the underlying service using a gateway-style approach.

61b888a: Remove path-scoped object extenders.

While workable for non-incremental requests, API for modifying existing deferred fragments would be quite complex.

39fcf37: Add source map support

6d3d2f6: Remove inlining

This change is a necessary precondition for adding potentially async transformations of the initial and subsequent results.