Fix non-pch build and remove blank line
Quest: Direhorn Raiders

Remove duplicate kill credit
Core/Misc: Fix some static analysis issues

Fix uninitialized values, most of which are false positives, always initialized before being accessed.
Add some asserts and additional NULL checks as sanity checks. Use SpellMgr::EnsureSpellInfo() if the spell id is valid and always supposed to return a valid not-NULL SpellInfo* .