Remove the matched orders in the order book received through message …

…MarketDataIncrementalRefresh.

Fix exchange meta data and support MarketDataIncrementalRefresh message.

Upgrade xchange-core from 4.1.0 to 4.2.0, and xchange-core-4.2.0 is n…

…ot compatible with xchange-core-4.1.0.

Upgrade xchange-core from 4.0.0 to 4.1.0, and xchange-core-4.1.0 is n…

…ot compatible with xchange-core-4.0.0.

Upgrade XChange to 4.0.0.

Add WebSocket API implementation.

Release artifacts to maven central repository.

Implement RESTful API v1.

Upgrade xchange to 2.1.0.

Implement official API using XChange.