Crate bill

Product and Invoicing primitives.

There is no difference between Invoices and Offers, so here there are only Bills. If you need to have Offers and invoices use two different Bills.

Structs

Bill	This is where the magic happens.
BillItem	Mapps a BillProduct to an amount.
Currency	Represents currency through an optional symbol and amount of coin.
ItemList	A list of BillItems, implements summing methods.
Product	Describes one particular product. Amount is handled by BillItem

Traits

BillProduct

Describes one particular product. Amount is handled by BillItem

Type Definitions

Amount
Money
Tax	Representation of Tax value