Fix for issue #37 - Multiple SetUp Fixtures should be permitted on same ...

This should make it possible to use more than one SetUp fixture per namespace. The order they are executed in is not defined and depends on the implementation of the .NET Framework.

I made a new commit and added a comment at this location. Note that I extracted a new method containing this code block.

I don't think that clearing the tests is an issue in this case, because they have already been copied to the new SetupFixture. The new SetupFixture will be the only child of the containing suite and the former children of the containing suite will be the children of the new SetupFixture.

I added a TODO that we should find a way to avoid the nesting of the SetupFixtures.