.NET Standard 2.0

[mrward]

Based on https://github.com/mono/mono-addins/pull/169 and includes extra fixes

• Includes Marius's changes to use an external exe for SetupProcess.
• Fixes a duplicate attributes build error with the MultiAssemblyAddin project

TODO:

• [x] Fix tests
• [ ] Review build warnings (18 warnings compared with 0 for the dev/mrward/ns2.0-rebased branch)
  • [x] Mono.Addins is not strong named
  • [x] Warnings about being unable to resolve references
  • [x] mautil warning about assembly conflicts
  • [ ] GTK projects do not build
    • GuiGtk3 does not build on dev/mrward/ns2.0-rebased branch - presumably not on master either
    • GtkSharp NuGet packages too new? Seeing errors about missing types (e.g. Gtk.SizeRequestedArgs) and missing methods (e.g. HeaderBox.OnSizeRequested) and non-virtual methods being overridden (e.g. Object.Dispose).
    • [ ] Clean up test lib directory.
      • Use logic from monodevelop to avoid local copying all the dependencies for the addins?
    • [ ] .NET 6 Setup process executable breaks tests

[mikkeljohnsen]

@mrward Is there anything I can do ?

[mrward]

There are still items on the TODO list which I will look at some point unless someone is keen to look at them.

Right now I have done enough to start looking at using this .NET Standard branch in VS Mac. After investigating this I will get back to addressing the other problems at some point.

[DamianSuess]

Looking forward to this. Thank you