Add enumerate example to bindings ZIP file
csharp: Use correct function ID for enumerate call
csharp: Close socket, stream and writers properly
cshrap: Fix auto-reconnect

Set socket to null on connection error to indicate disconnected state.
csharp: The callback thread needs its own reference to the callback queue

Otherwise the callback thread might access a null reference when the
disconnect function removes the main reference to the callback queue.
csharp: Update assembly copyright year
csharp: Remove redundant check for socket != null
csharp: Don't trigger a disconnect error callback on disconnect request
csharp: Don't assume that CallbackQueueObject data is always a packet

CallbackQueueObject data can also be null for QUEUE_EXIT, for example.