New campaign added: "Wan Li"

I have added the "[You must be registered and logged in to see this link.]" campaign.

As always check the dynamic list of campaigns for the latest changes:
[You must be registered and logged in to see this link.]

Note:

After testing the campaign on Realism we recognized that the campaign scripting in the vpk only can handle "coop" and "versus" (final map was buggy and escape was not possible).
I've modified the scripts in the vpk so that the campaign also works for "realism".
Clients can use the campaign from l4dmaps.
The improved vpk is only needed on the server.