Preview: Support for equippable items (items to be used during animations)

This will be part of v1.13, releasing on Friday.

Finally added support for loading / managing / unequipping tools. Compared to traditional accessories, tools can have multiple assignment points / holding positions. E.g. the item in the example clip can be equipped in either hand, top-up or top-down, depending on what the animation needs. The decision for which tool variant (assignment point / holding position) is being equipped belongs solely to the animation.

Above is a simple animation (work in progress, not final), demonstrating the new equippable tools capability.

You can see the first item I added. It's equipped / unequipped automatically for the appropriate action(s). It's not going to be a user facing thing, and no customizations (i.e. materials / colors) are available at this point. In time, I will be adding various other items, together with new animations that make use of them.

The plan is to try and offer customizations sometime in the future (that's probably going to happen once the concept of inventory is implemented).

The above animation will be coming as a post defeat action, and will also be part of the endurance training that's coming next.