Support keyboard navigation

Keyboard navigation seems like an useful tool that makes sense on Desktop Icons' fixed grid.

Also maybe multi-select files with Shift+Arrow Keys? But I would like your thoughts on that, because even though I think it would be useful (and pretty intuitive), I'm not sure how that would behave, and if it makes sense on Desktop Icons. Would it have a "+ single file" behavior (just like clicking on another file with shift pressed on Desktop Icons), or would it have a "rubber band selection" behavior? On my mind that last option would be something like drawing a polygon with the keyboard arrows, represented by the filthy diagram below.