Making an offer no longer needs a nonce. Instead, a user counter is required. Every time the user cancels all offers, his user counter gets increased by 1.
Making offer API now accepts an size parameter. Passing in a integer larger than 1 creates a loan offer that could be accepted multiple times.
When making collection offer, the TokenId should be set to "340282366920938463463374607431768211455" which means "0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", instead of a null value.
