[1.2.179] Lots of changes to Night Walker

Psh, look at the Nightwalker thread for the changes.

- Sudden Attack requires 10 points in Dark Sight
- Vampire greatly weakened
- Avenger weakened
- Venomous Star weakened
- Few skill icons changed

I still don't see much difference. They weakened everything to make L7/TT the skill. >_>;