If a heartbeat timeout occurs skip calling SSL_shutdown as it involves doing a
send() which will likely hang. Additionally don't wait for a response when doing
an SSL_shutdown, as the underlying transport will not be reused.

Fixes #313

Fixes #293

Don't initialize local variable last_error because it is immediately assigned to
and value is not used.

Removed superfluous and suspicious cast in amqp_simple_rpc() call. 'replies' is
already a amqp_method_number_t*

Use logical-or instead of bitwise-or in preprocessor conditional.

Fixes #295

Add amqp_ssl_socket_set_verify_peer which controls peer certificate validation,
and amqp_ssl_socket_set_verify_hostname which controls hostname validation in
the certificate. Additionally this deprecates amqp_ssl_socket_set_verify.

Fixes #180, #279, #303

When doing a nonblocking connect() on win32, select() reports failure using
exceptfds instead of writefds. Allow this narrow case when doing a non-blocking
connect on Win32.

See:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms740141(v=vs.85).aspx

Fixes #297