Improve customizability of prefabs

[don-tnowe]

The tooltip is rather customizable: give it a bunch of scripts that call text- or node-adding functions, and you've got it showing properties. You can even (since 3d9690cdf0fe08501254cd5b387ecc8c24348bcf) change the styles and swap colors around. The other nodes are, however, not as open to tweaks.

Editing the prefabs is still an option, but not really ideal - you'd be modifying a part of the addon! And sometimes you'd need to modify the script, which is even worse!

• In-inventory ItemStackView only shows item image, back-color and count. What if someone would want to show durability or enchantment level?
• GroundItemStackViews, both, can't really be customized much - I'd like to allow developers to just slap the ground item script onto any object and make it work with the bare minimum.
• non-grid InventoryView is a bit wonky since it copies the first slot in the container, but I might just add a "slot prefab" property and call it a day.