[macOS] Implement library port to macOS platform

[vbovasia]

Implement library port to macOS platform that requires a separate framework for macOS platform.

[stevengharris]

I have no plans to support MacOS, only Mac Catalyst, but I don't think it would be hard to pull together. If you've done it or worked on it, let me know. Thx.

[martindufort]

I also would be interested in a macOS version of this library. Anyone know if a forked version for macOS is underway?
Thanks

[stevengharris]

Fwiw, I have not heard of anyone working on it and have not tried myself. If you're going to look into it further, perhaps we could use a Discussion to track how it goes. I just opened up the Discussions area for the repo.

[martindufort]

Thanks for that. Let me see how that goes.

FYI: Just discovered that WKWebView class on macOS undertands commands issued by the NSFontManager and pretty much does what you are doing with this project.

Will post findings in the Discussions area.