Added .close() and .flush() method
Added ability to append packets to a pcap file with the append parameter
Added ability to make synchronous writes withe the sync parameter

Added Packet.setfieldval() and Packet.delfieldval()
(Ticket #86)

(G. Valadon, tickets #77 and #78)

StopAutorun can be raised in a piece of code aimed at being autorun and will
not be catched by autorun_* functions

Now, instead of creating one add-on for each new protocol, and launch each
add-on separately, you can put some load_extension() commands in your
~/scapy_startup.py and each time you run Scapy, all your extensions will
be present.