title: Assign a friendly name to a data set item provided to an xUnit Theory, to be used for display in the results after the theory name
body: <p>I have started to use xUnit for unit tests. I have some test code working, and one test failing. The test data is provided via a MemberDataAttribute to the Theory.
  When the tests are executed in Visual Studio Test Explorer I see the outcome of the tests, many passing, some failing. </p>
  
  <p>The results look like TestCaseName(expected: 1234abcdef1234abdc....) where I see the hashcode of the object[] used as argumentum list for the invocation of the Theory method (or at least i presume it is that). </p>
  
  <p>This is generally OK, but I'd like to know if there is an elegant way to provide a hint to xUnit to display some test dataset item identitifier for the individual cases? </p>
  
  <p>I think it is clear how much easier it would make to navigate the test results with respect to the input data, and this is why I'm convinced that a solution is already provided by the framework.</p>