Target netstandard2.0

[cocowalla]

There are warnings when using this library from a .NET Core or Standard project - would be good if this library could target netstandard2.0.

Technically .NET Standard 2.0 libraries are compatible with .NET Framework 4.6.1, but I have seen some issues in practise, do if you decide to go ahead with this, and still want .NET Framework 4.6.1 support, it might be a good idea to target both net461 and netstandard2.0.

[kendallb]

The C1 library cannot work in .Net standard (but they did just release a new .Net 5 version). I will see if I can re-target the non-C1 version for standard 2.0.

[kendallb]

Nope, not gonna work as we use System.Drawing as part of the API. The only path forward would be .net 5 at some point.