BW & XY: Implement Recycle.

- Correct a few item interaction mechanics as well.
I called it `restore` because effects that restore your last used item (Recycle and Harvest) reset your last used item since you're technically currently holding it. It took me some time to figure out how the game might have implemented this to prevent stuff like Harvest from giving your item back after a Knock Off. I agree though that at first glance it doesn't make much sense, and your suggestion of `clearLastItem` is probably as good as it gets for clarity. I'll change it up when I get a chance!