title: OpenCover shows code coverage for C# projects but not C++ CLI native project
body: <p>I have a large visual 2013 solution composed of 20+ projects paired with test projects that use NUnit for unit testing.  All of these projects are straight C# except one with that wraps an external C++ class which uses C++ CLI. The wrapper class is unit tested in C#.  OpenCover displays the info for all of the C# classes including the parent classes of the wrapper but excludes the coverage for the C++ methods.  Is this a limitation of NUnit and/or OpenCover or "user" error?</p>
  
  <p>When I peer into the output directory, I can see the wrapper class xml, dll, and pdb.  When I run ReportGenerator on the native dll's xml, I can see the C# classes.</p>