migrate to netstandard 2.0

[ygalbel]

I tried to migrate the project to newer dependencies and frameworks.

I hope we can publish a new version of the nuget.

[LawrenceSmith1437]

Shame this is left on the front porch in the rain.

[reustmd]

If someone wants to pick it up as a collaborator I'm fine with that, I haven't been an active C# developer for many years.