Troubleshooting visualizer installation

1. In order for the visualizer to work, the files need to be unblocked. This is usually available through the Explorer UI, by right-clicking on the file and selecting Properties:

and checking the Unblock checkbox.

2. The visualizer is currently tested with Visual Studio 2017. It has also been reported to work with Visual Studio 2019 Preview 4, but only in the Documents\Visual Studio 2017\Visualizers folder (not the Visual Studio install path); and then only in a subfolder called netstandard2.0. This restriction will be lifted by the time Visual Studio 2019 RTM comes out.