Improve accept() throughput and fix connection blockade due to accepting Connection and SERVER_PROTOCOL headers.

Process requests within a goroutine after Accept() to allow new connections to come through; such is the case where there is a large POST request which could clog the connection listen queue.

Also force disconnection after processing one client connection by ignoring Connection and SERVER_PROTOCOL headers.

The other thing I've added is to not read the request body into the buffer, since it could be a big payload. Rather, after the headers have been completed, the Read() will transfer to the connection's socket. This eliminates the need to buffer multiple times.