[#133] Storage sheet

[krbz999]

• Creates mythacri-scripts.storage system actor type, with associated sheet.
• The actor will not allow for class, subclass, or any other items that do not have a quantity.
• Dropping a spell onto the sheet anywhere will create a scroll.
• Dropping consumables will stack, as usual.
• Dropping loot will not stack.
• Dropping loot that is a crafting resource will stack.
• The actor can be configured to track capacity in quantity or weight.

Closes #133.