Moved Assert.(Not)Same into IdentityAsserts and Assert.(Not)Null to NullAsserts.
Move DiaSession code to VisualStudioSourceInformationProvider. Update Visual Studio runner to support v1 and v2 tests.
Removed xUnit.net v1 source. Renamed src2 -> src, test2 -> test.
Performance: cache instances of fact discoverers. Add some more potentially useful warnings.