Windows: use Winpcap, drop DNET dependency

self-merge since @guedou is OK and @n1nj4sec agrees.

Use the provided interface in attach_filter()

This is related to the e-mail thread[1] on Scapy mailing list, based
on the proposed PR on Bitbucker Suraj Deshmukh [2].

[1] http://article.gmane.org/gmane.comp.security.scapy.general/5297
[2] https://bitbucket.org/secdev/scapy/pull-requests/127/issue-5121-now-iface-option-of-sniff/diff

Fix ipsec for Python 2.5 (fractions module does not exist)

Initial Pcap-NG support

fix support for powershell and fixed some warnings when sending packets on XP

fix support for powershell (tested on windows 7) and fixed some warnings on winXP when sending packets

Linux: L2Socket can set promiscuous mode (fixes #17)

Return Raw() when an exception occurs in .dispatch_hook()

... if not conf.debug_dissector

Idea from @paaguti in pull request #10.

ls() can now filter by layer name or description

Use list comprehension in diffplot()

Fix for Python 2.5 (cannot mix keyword arguments and **kargs)

Use __slots__ for some Scapy objects

Under Windows XP, the InterfaceIndex in Win32_IP4RouteTable does not
match the InterfaceIndex in Win32_NetworkAdapter, we have to use the
IP addresses to match interfaces to routes.

Rename argument / attribute "set"

Add optional parameter plot_xy to .plot() and .multiplot()