I promoted the beta to be the main website today. If you are experiencing bugs or things aren't working as expected, the old interface will continue to be accessible from old.markwhen.com.
I started a new repo when redoing the frontend, so the repo at kochrt/markwhen is out of date. I am still using it for feature requestes and bug reports, but yes the code there is stale. While rebuilding I split things into roughly three parts: the parser, the renderer for displaying the timeline (basically everything but the editor), and the full website/editor, each one built on the last. I don't think the full website will be open-sourced. I intend for the renderer to be, but I got tired of trying to keep things separate because of how much extra overhead that was, so for the last ~2/3 weeks I have just been building in the website repo and not in the renderer repo.