View/Store constraint violations and justifications from benchmarker

It would be nice to have something within the Benchmark API to provide output of the ConstraintMatchTotal/ConstraintMatch/Justification graph, to enable quick debugging of rules and other related problems from a simple benchmarker app, without having to go round the loop of running your own app to interrogate that information.

A UI for visualising the data would be nice, and maybe an XStream output of the object graph so that people can write tools to interrogate the data.