Allow mouse use during controller gameplay

I'm not sure why the control schemes are so segregated that you actually need to log out to switch control devices. Every other game, including the infamous D4 lets you change control types on the fly during gameplay.

That said, what I really want is the ability to control my inventory and stash using my mouse while gamepad is my selected control scheme. Organizing these stashes is basically impossible with a controller once it fills up enough, that I have to log out, change to Mouse, log back in, organize inventory, log out, change to controller, log back in.

Let's get this basic pre-alpha feature implemented please.