Document API platform differences

[karelz]

We need to document API differences:

1. Between .NET platforms -- .NET Framework vs. .NET Core vs. .NET Native vs. Xamarin/Mono, and
2. Between OS's -- Windows vs. Linux vs. Mac

The documentation should be exposed as platform-compat tooling and also as standalone HTML.

[karelz]

Update also porting.md - AppDomains with link to differences.

[tarekgh]

@karelz do you think this can be done in v2.0 time frame? I think this will need sometime to cover such differences

[karelz]

This should happen in 2.0 timeframe - it is part of the platform end-to-end. It might be exemption to ZBB on 5/10 though.

[karelz]

BTW: The content/list of differences is now being collected here: https://github.com/dotnet/corefx/wiki/ApiCompat

[ViktorHofer]

@karelz Post-ZBB label maybe?

[karelz]

Yep, good catch. Thanks @ViktorHofer!

[tarekgh]

@karelz are you following in this? will be able to close it before the end of the week?

[karelz]

I will follow up. Documentation changes can happen after Escrow ;) as they don't require code change.

[karelz]

The tooling was released as preview via nuget: https://blogs.msdn.microsoft.com/dotnet/2017/10/31/introducing-api-analyzer/

Source code is here: https://github.com/dotnet/platform-compat