Sandboxing the application

Is it appropriate to [sandbox MacDown](https://developer.apple.com/library/content/documentation/Security/Conceptual/AppSandboxDesignGuide/AboutAppSandbox/AboutAppSandbox.html)? I think this is more friendly to end users. In addition, I may want to publish it to App Store when I get rich ^/s.

Start by reading the linked Apple App Sandbox Design Guide and the repository description to understand the proposed change for MacDown. Determine whether sandboxing is feasible and what App Store publication would require; done means the project has a documented decision and scope.

Written by the indexing model from the issue text.