Improved close behaviour, shutdown receiving end even if there are async writes pending.
Improved close behaviour, shutdown receiving end even if there are async writes pending.

AlwaysRightInstitute/SwiftSockets,luosheng/SwiftSockets,AlwaysRightInstitute/SwiftSockets,AlwaysRightInstitute/SwiftSockets,adrianomazucato/SwiftSockets,adrianomazucato/SwiftSockets,luosheng/SwiftSockets