Preferred Item slots improvements

Preferred item slots are great. I know that if I get a zhonya it will be on 6. But there are several edge cases that don't work:

• New support items don't let you set a slot at all, and they move around when you upgrade. We need to be able to set a slot for each level of upgrade, since you may want something else on the easy button (like potions) before the warding totem active come online.
• Rune items don't have an option at all. We need to specify where biscuits, watches, boots, etc. are gonna go (especially the first two, or you try to heal or invul and get the wrong button).

Also, we need a way to set secondary slots. If I have Zhonya and Randuin, I need to have Randuin go to slot 3, not 6 as the zhonya is already there. There are enough active items that a single slot assignment may have overlap in some situations, especially for supports who love to stack active items.