AMQP-CPP 4.1.7

• deferred-chain was kept in scope by a consumer-operation, this fixes #323
• fix bug in Channel destructor for objects that were already moved
• prevent crash when channelimpl unregistered from the connectionimpl, (hopefully) fixes #299 and fixes #326
• added Channel::ready() method
• The onFinalize() callback could be called more than once, which is not ok
• fix compiling on freebsd (fixes #300)
• the TcpConnection class no longer calls back to userspace / to the user-supplied handler if user-space explicitly destructs the object