.NET Core Support?

[Lakritzator]

Check if it's feasible to get the functionality in .NET Core.
This Blog-Post: https://weblogs.asp.net/ricardoperes/using-mef-in-net-core makes clear that it's possible to use MEF inside .net core, so maybe it's enough to support this library.

[Lakritzator]

According to the diffs for .NET Core 1.0.1-> 1.1, the composition namespace should have been added.

[Lakritzator]

I want to review this API as soon as the .NET Core 3.0 APIs are clear, it should be possible to use Dapplo.Addons for Greenshot on .NET Core 3.0 (or delete this project, as it's not longer needed)

[Lakritzator]

Currently the project seems to work with dotnet core 3.0 just fine.
I believe AppDomain exists, but I have read about a much lighter way of loading assemblies from Rich Lander, who wrote something about it here: https://github.com/richlander/dotnet-core-assembly-loading