Fixed command line argument handling when using IPython

With IPython support enabled, any command line arguments
given to Scapy were incorrectly interpreted by the embedded
IPython shell as IPython command line arguments.
For example, "scapy -d" (to increase Scapy's debug level) did not work.

scapy/main.py

@@ -308,7 +308,8 @@ def attr_matches(self, text):
 
     if IPYTHON:
         banner = the_banner % (conf.version) + " using IPython %s" % IPython.__version__
-        ipshell = IPython.Shell.IPShellEmbed(banner = banner)
+        args = ['']  # IPython command line args (will be seen as sys.argv)
+        ipshell = IPython.Shell.IPShellEmbed(args, banner = banner)
         ipshell(local_ns=session)
     else:
         code.interact(banner = the_banner % (conf.version),