QVT14 — QVTo: Enhance Status to support access to nested transformation trace data

Transformation::transform()/parallelTransform() support a nested invocation but the returned Status content is very limited.

Suggest 1: Reify TraceData/TraceRecord so that arbitrary OCL queries can be executed.

Suggest 2: Add a getTraceData() to Status and 'this'.

Suggest 3: Add an optional Status first argument to all resolve() methods to enable use on an invoked Transformation.

NB. Since a transformation invocation involves cloning, resolve() should hide the clones so that the caller sees only a single object space.

Suggest 4: TraceData/TraceRecord/Status/Transformation/Model should be / share share an abstraction with QVTc/QVTr.