title: add option in tcp with scapy
body: <p>Upon the receive of a TCP ACK (with option experiment) like this</p>
  
  <p><img src="https://i.stack.imgur.com/8Vcg9.png" alt="enter image description here"></p>
  
  <p>I want to generate a TCP SYN+ACK (with option experiment and Fast Open Cookie) as indicated below</p>
  
  <p><img src="https://i.stack.imgur.com/78jP1.png" alt="enter image description here"></p>
  
  <p>I want to generate the TCP SYN+ACK with scapy so I added</p>
  
  <p>So I added <code>254 : ("RFC3692-style Experiment","!HHH")</code> in the /<code>usr/share/pyshared/scapy/layers/inet.py</code> like this</p>
  
  <pre><code>TCPOptions = (
                { 0 : ("EOL",None),
                  1 : ("NOP",None),
                  2 : ("MSS","!H"),
                  3 : ("WScale","!B"),
                  4 : ("SAckOK",None),
                  5 : ("SAck","!"),
                  8 : ("Timestamp","!II"),
                  14 : ("AltChkSum","!BH"),
                  15 : ("AltChkSumOpt",None),
                  25 : ("Mood","!p"),
                  254 : ("Experiment","!HHHH")
                  },
                { "EOL":0,
                  "NOP":1,
                  "MSS":2,
                  "WScale":3,
                  "SAckOK":4,
                  "SAck":5,
                  "Timestamp":8,
                  "AltChkSum":14,
                  "AltChkSumOpt":15,
                  "Mood":25,
                  "Experiment":254
                  } )
  </code></pre>
  
  <p>And upon the receive of the TCP ACK (with experiment option), I executhe the following scapy function:</p>
  
  <pre><code>TCP_SYNACK=TCP(sport=Ddport, dport=Ssport, flags="SA", seq=SeqNr, ack=AckNr, options=[('Experiment',0xf989,0xcafe,0x0102,0x0002),('NOP',0),('NOP',0)])
  ANSWER=sr1(ip/TCP_SYNACK)
  </code></pre>
  
  <p>But I got a python error. It looks like I made error in the definition of the option field in the TCP packet with scapy. What I m doing wron?</p>