Core/Spells: Remove correct stack of Deadly Poison when using Envenom
Merge pull request #10178 from mweinelt/master

 Core/Spells: Remove correct stack of Deadly Poison when using Envenom
Core/Scripting: Allow Headless Horseman to be attacked

Fix by digz6666.
Note: this script needs rewrite, any pull request doing it is welcome.
Closes #3568
DB/Gossip: Fix a previous commit.
Merge branch 'master' of git://github.com/TrinityCore/TrinityCore into teste2