Scripts/Halion: Fixed Soul Consumption's pull effect.

Thanks to Winterfell for pointing out the issue.
Core/Entities: correct creature damage, offhand damage should work too
* todo: some creatures need dmg_multiplier update in creature_template
DB/Spells: remove duplicate/invalid entries from spelldifficulty_dbc
* For new entries: use spellid0 as id to avoid conflicts with dbc file
DB/Spells: correct more spelldifficulty_dbc entries
* add log message to find wrong entries
Core/Threading: Handle CMSG_ZONEUPDATE only in WorldSession update - changing zones triggers changing chat channels, what is not a thread safe operation
Scripts/HoS: update Maiden of Grief