Bugfix release

Two bugs were fixed:

• A crash that would occur when a connection object received data just (milli seconds) before it was closed.
• A bug that would cause connection objects to go missing when a connection was accepted, but no data was ever received. This was a fairly common occurrence and would result in a non-response server.

Unfortunately this necessitated the change of 1 interface in Connection.swift: 'receiverData' is now supplanted by 'processReceivedData'.