Fix: default iface detection when IPv6

Signed-off-by: Gregory Detal <gregory.detal@uclouvain.be>
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Signed-off-by: Gregory Detal <gregory.detal@uclouvain.be>
Modify WindowScale

Now use the new object TCPOptionWindowScale of libcrafter.

Signed-off-by: Gregory Detal <gregory.detal@uclouvain.be>
Add basic support for packet modification

The modified fields will be displayed at each hop

Signed-off-by: Gregory Detal <gregory.detal@uclouvain.be>