Feature Request: Add Portable Installer option

[MasterRee]

Looks really promising so far! This is a feature request. It would be so helpful to have an option on macOS (and presumably Linux and Windows as well) to perform a portable install. To be clear, I mean an install that is entirely contained in the directory wherever the user chooses to place the application, instead of having configuration files in the home folder, user or root libraries. Some emulators trigger this when the user creates a portable.txt file next to the application.

EDIT: This is especially valuable to install all emulators and related content on a single external drive that can be moved between devices or can provide an immediate plug'n'play gaming experience if you need to wipe your computer.