Move console listeners to console project

When cross-AppDomain communication was first introduced, the Listener implementation involved input arguments that were not serializable, so attempts to instantiate Listener objects on one side of the AppDomain boundary and use them on the other would fail with mysterious error messages.  The temporary workaround was to place the two console-based Listener implementations in the wrong assembly, so that their usage would be entirely on one side of the AppDomain boundary.

During the recent implementation of the Visual Studio runner, this poor definition of the Listener interface came to light and it was improved so that runners (like Fixie.Console.exe) can now define their own listeners, and pass them over the AppDomain boundary to be used at runtime.  Fixie.dll no longer needs to know about the Fixie.Console.exe's Listener implementations, so this pull request moves them to their proper home in Fixie.Console.exe.