Auto Formatting / Beautifying

It'd be useful if this editor integrated auto-formatting. Something like [tidy-markdown](https://github.com/slang800/tidy-markdown) should do the trick. Then one could just have an option for doing it on save or with a key combination.

The issue proposes tidy-markdown and requests integration with the editor. Review how the editor currently handles saving and key combinations, then define whether formatting should work on save, through a shortcut, or both, with the resulting Markdown formatting as the completion criteria.

Written by the indexing model from the issue text.