Figure out better design for item folding

[MikeHopcroft]

When CartOps.itemFolding is false, the nine unit tests listed below fail. The question is, when one attempts to add an item to a Cart, should the item adjust the quantity or modifiers of an existing item, or just add a new item.

Example 1: "1 grande latte and 2 grande lattes" - does this result in two line items, for a total of 3 grande lattes or does it result in one line with 2 grande lattes?

Example 2: "grande latte remove the grande latte" - does this result in an empty cart or two line items, one for a grande latte and one for zero grande lattes?

CartOps
Updates
√ add standalone top level
1) remove standalone top level
√ add default to newest
2) modify default in newest
3) remove default from newest
√ add default to older item
4) modify default in older item
5) remove default from older item
√ add option to newest
6) modify option in newest
7) remove option from newest
√ add choice to newest
8) modify choice in newest
√ add modification to choice in newest
9) remove choice from newest