Make sio_read more extendable and fix his memory leaks
Make sio_write more extendable
Use the rigth len when writing a structure.

Before, it used the full length instead of the actual lenght.
Fix a test and again, use the current length instead of the max length.
Fix typos in packet.{c,h}
Comment test_packet.c
Give PACKET_TEST a rigth ID wich don't collision with others