Nerf pillar-dancing

[VeryAngryFelid]

I hope I don't need to list reasons why pillar-dancing is bad.
http://crawl.homedns.org/crawl#lobby nerfed it by changing movement cost depending on direction. So you can still run away if running in straight direction. But if you try to run in circles you get a severe movement penalty (up to 20 auts even as hasted spriggan) so it can kill you.