Support Partial Filling of Offers

[nobu-maeda]

Duplicate of Issue #2, as that original issue have deviated in the course of discussion. This as such is now the actual issue to track the original topic.

One of the key limitations Bisq and RoboSats has is that Maker offers are often very rigid. If a Maker have a buy offer for 0.1 BTC, a Taker hoping to buy only 0.01 BTC cannot take that offer.

Ideally, the protocol should be able to support such that an offer can be taken partially, and thus multiple times, before the offer is considered fulfilled and invalidated. Whether this is enabled depends on client implementation and potentially an option to the Maker. Ultimately whether a partial fill is acceptable to the Maker is up to the Maker and client implementation/defaults. The protocol level should support and not prevent this.