Add project Fixie.TestDriven, for integration with TestDriven.NET.
Add third-party library TestDriven.Framework.dll.
Fix variable name.
Listener listens for passing Cases in addition to failing Cases.  MethodCase writes success to the listener.
All deployable projects use build/ as their Output Path.  This is a prerequisite for TestDriven.NET integration: being able to use TestDriven.NET within this solution, using Fixie as the test runner, requires that Fixie.dll, Fixie.TestDriven.dll, and a *.tdnet support file all be located in the same place.  This build/ folder mimics the end user environment too, in which all these files would be deployed in a NuGet package.
Fixie.TestDriven.dll depends on Fixie.dll and TestDriven.Framework.dll.
Initial implementation of TestDriven.NET integration.  Known limitation: when attempting to run a single method, this currently executes the whole fixture containing that method.