I'll clean up this PR tomorrow (remove most whitespace-only/swapping-declaration-order changes) and fix build (feels like CI VSTest problem, everything works locally). But I consider this ready for review, since it is feature-complete. With this, diff to my local 2.0 branch reduces substantially.

Removed docs extensibility will return (greatly rewritten) in the Episode 6 PR, since Episode 5 will be about merging MSBuild tasks and reworking cache invalidation.

@jkoritzinsky

Upd: merge without squashing! Otherwise, the commit history of SDK props and targets (renamed to Sdk.props and Sdk.targets in the 1st commit) will be lost.

@jkoritzinsky any plans to update this project? Tell me because my Vortice.Windows depends on SharpGen, otherwise I gonna keep personal fork

@amerkoleci btw, you might be interested in my mostly complete Microsoft Docs doc provider that will enable you to fix amerkoleci/Vortice.Windows#69 automagically. I am working right now on C# 9.0 function pointers native invocation impl, but I will push everything as soon as I consider it to be mostly working. #161 is my primary dev branch.

Any chance we get update on nuget? At least for the runtime part?

I'm working on preparing Episode 5 PR right now. I also have no objections to creating first 2.0 beta release, since it will allow for early 2.0 feedback. If @jkoritzinsky concurs this is the right thing to do, creating a tag should automatically publish a NuGet release.

I might need to update our NuGet API key for publishing a new package, but other than that we can create a 2.0 beta 1 release.

I think having beta release doesn't hurt and can help others to test it