Code to verify that the outbound on-the-wire MPLS label stacks from
the kernel under test match those from the script.

Change-Id: Ib7e4e4dc04cdd8d760c8099948f7cdda7973202a

Basic verification for outbound encapsulated packets from the kernel
under test.


Change-Id: I5efeb08fb262312ec85d257680e4df46829a38f0

The main engine for handling encapsualted packets in packetdrill,
including:

- parsing scripts with encapsulation
- parsing packets with encapsulation
- injecting packets with encapsulation

Encapsulated packets look like the following, which has an IP header,
GRE header, and then regular IP/TCP header:

+0 > ipv4 1.1.1.1 > 2.2.2.2: gre: . 1:1001(1000) ack 1

See other patches in the series for more detailed examples.


Change-Id: Ia8c7580e268f5b0347bd9d3fdc73b096f751a79d

Initial commit for the packetdrill network stack testing tool:

  https://code.google.com/p/packetdrill/



Signed-off-by: Neal Cardwell <ncardwell@google.com>