Add IDs to items, add more functionality to Inventories

[alicerunsonfedora]

This PR makes the following changes:

• Adds an optional itemId type to ASInventoryItem
• Implements new export, getItemById, and removeItem methods in ASInventories
• Deprecates retrieve in favor of export
• Updates addItem with a silent parameter to stop flooding of notifications if unneeded
• Updates documentation with new Inventories changes

[alicerunsonfedora]

Noting that export is a function that takes a function as its parameter to filter the items. For example, to grab IDs of items using export:

idOnlyFilter = lambda item: item.itemId
exportedInv = inventory.export(idOnlyFilter)

(This makes use of the map function to apply this filtering down).

[alicerunsonfedora]

Performing executive order and merging.