Feature idea: use other user's inventory as input.

[exurd]

This would allow badges and favourites in a user's inventory to be a valid input.

Ideas on what the comma-comma strings could look like:

• user-badges:: (too similar to player badges, does not imply it's for user inventories)
• userinv-badges:: (userinv feels clunky)
• inventory-badges:: (doesn't imply user, but it's easier to read)
• inv-badges:: (short for inventory)
• ui-badges (short for user inventory)

Something like inventory-badges::, inventory-places:: (to replace user::), inventory-favorites::?
The API for badge inventories allows for ascending and descending order, so adding _ASC or _DESC before the :: should specify the order.