Ability to define and easily install extensions

[davesmith00000]

The roguelike work and the UI work is getting bigger and more complex, and the set up for the user is also getting more involved. Perhaps we can make it easier with an extensions system where the UX is: 1) add the dep, and 2) register the extension.

Extensions add requirements like shaders and subsystems and clones/prefabs to the game.

Any merit in that? Could other things like physics become extensions?