fix split writes for long server responces

The client is reading the servers repsonses in a non-blocking environment and will not cope if the stream does not contain all of the expected data. This leads it to read an "answer included" response and not find the expected size. Leading to unexpected command failures. . Guarentee the entire message is available by packing the various parts into a buffer and submitting it as a single unit. This will ensure as far as possible that we will not get the first byte without the rest being present. . In a perfect world the consumer would cope with short buffers, and internally buffer those until the remainder arrives.