Releasing v1.0.0

[tig]

All - esp @migueldeicaza

We've got a few fixes to NStack that we'd like to deploy to support Terminal.Gui.

I've done more work on the repo to make it more modern:

• Now uses gitflow style branch model (main always represents last published package/develop for current work)
• API docs are now generated from main via a GitHub Action

NStack has been very stable for a long time and I think it's time it gets a "v1.0" version #.

Any objections to me making the next release (which otherwise would be 0.18) be "Release v1.0.0"?

[BDisp]

For me I agree at all. It's a very good support for Unicode.