[svn] Add function GameObject::CastSpell. Used for hunter's trap and so.

Use original caster instead caster to check spell hit result.
Let spell triggers have the same faction as the summoner.
Fix the bug that trigger creatures attack enemy. (no need use civilian extra flag in the future, 128 is enough)
Fix shadow step.

--HG--
branch : trunk

sql/updates/153_world.sql

@@ -0,0 +1 @@
+update creature_template set flags_extra = 128 where entry = 12999;