XMLUnit 2.10.0 doesn't work with NUnit 4.x

[bodewig]

see #41 (comment)

[ScottWrightWTG]

I was thinking if the Description could be set there would not be an issue. In the constructor for the static calls you could force a description but that is a breaking change, but it would work. The only other way is to add a different instance constructor that allows setting the description and then remove the static Instance calls. Again breaking change

[bodewig]

Worst case I'd create a new constraints-nunit4 project if we cannot find a reasonable way to make things work for 3.x and 4.x at the same time.

Right now I'm struggiling wth my local setup since I need an oldish Windows VM for the ancient framework versions XMLUnit still supports. It may take some time until I can really take a deeper look - in particular since time is something I currently lack anyway.