inner mock Async API mostly working

Copy of year-old work, plus
- edits to make unit tests pass
- Fix up ancient stuff in csproj files
- add skeleton for implementations
- add readme
tidy up readme
Add first implementation (async with APM and anonymous delegates)
Implement TaskWrapper and Async/Await.   Did not implement AsyncEnumerator, probably easier to make a reference to it but not include it.
Readme much clearer

Implement CallbackSeparation
some comments cleanup
fix blocked thread in AnonymousDelegates
Adding licensing info, and some comments
Ready to push to github!

- simplify AsyncAwait
- check in rest of licensing stuff
- remove AssemblyInfo.cs from all projects
ready to push to github!  (files left out of previous commit)