Rename SQL files. It's not November, yet.
DB/Spell: Delete no longer needed hack

By unholychick
DB/Spell: Do not let Ebon Plague stack from different casters

Closes #12314
Updates #1818
By unholychick
Update README.md
Core/Misc: Fix current player state when logging out

Sit should only be apply'd when player is standing.
For example when sitting on a chair when logging out, player should stay on the chair until fully logged out and not sit on the floor.
DB/SAI: Prevent endless loops with linked events
Revert bfc6044
DB/Loot: Xandivious (15623)
Core/Maps: Apply const-correctness to GridMap::loadData()
DB/Loot: Xandivious (15623) - forgot item 12002

Thanks @Aminxhm
Merge pull request #13321 from Kittnz/unit_state

Core/Misc: Fix current player state when logging out
Merge branch 'master' of github.com:TrinityCore/TrinityCore into 4.3.4

Conflicts:
	src/server/game/Handlers/MiscHandler.cpp