Modified recvAllNB() to return an empty string (instead of NULL) if there is nothing to read

includes/sock.hpp

@@ -49,7 +49,8 @@ public:
 	/* Method to receive data sent to the 'other_socket' socket */
 	char* recvAll();
 
-	/* Non-blocking receive method - calls the method above after polling for data */
+	/* Non-blocking receive method - calls the method above after polling for data. Returns
+	an empty string if there is nothing to read. */
 	char* recvAllNB();
 
 	/* Returns socket identifier */