Added the new version for dummynet.

The new code is located into the dummynet2 directory and the spec file
was changed to used this latest version.

Major changes related to PlanetLab are the new table lookup support,
a little fix to accept packets after the reinjection and code cleanup.
The new table lookup support will allow a PlanetLab user to jump
directly to their own rule section, avoiding to scan the whole
ruleset list.