Add a samples library.
Reorganization of sample content

Make a separate sample project. Move old sample content out of RTF into
the sample project. Move a base rfa file and addin into the tools
folder.
Ensure all projects are using the same NUnit.
Add some tooltips and a Run button.
More UI formatting fixes.
Exception handling.

Add the empty.rfa file to ensure there's always something to open.
Don't try and load results if there are no results to load.
Make sure the run button has a command parameter.
Show the model name next to the test name.