Adds new hotkeys for moving the item in the next and previous quickbar slot into your hand.

The implementation is a little strange, due to the fact that we can't actually switch which quickbar item is selected, so it keeps its own internal counter and draws a little pointer to the active bar slot from the mod.

The default keybindings for next and previous quickbar slot are . and , respectively.

Right now it allows you to scroll through your top two quickbar slots, but I might be limiting it to 1 bar in the future. I want to actually build some experience using it first before finalizing any of those settings.

0.2.0 - Add a few more keybinding for some helpful utility quickbar functions
0.3.0 - Use location instead of padding for the GuiElement. Apparently I was just making the element really large the other way, causing placement issues.