[1.6 beta]Fixed undead Boss shouldn't have wild-gift talents

[starsapphire]

Currently, most undead enemy have `not_power_source = {nature=true}`, which means it is impossible to find something like a randboss skeleton summoner or oozemancer
However, some fixed boss don't have these property. The undead trio in dreadfall is an example, because they are not derived from base undead NPC, they don't inherit this property. While most of them will be fixed in 1.6.0 because they now have fixed clases, the undead trio and the Shade of Telos don't have a fixed class, and still fell into victim of it.
Though we already have Z'quikzshl, and adding an antimagic undead unique may not be bad idea , but this exception itself is a bit inconsistent and may be a bug to be fixed.

[darkgod]

fixed