Core/Battlefield: move complex methods from BattlefieldWG.h to BattlefieldWG.cpp
Core/Battleground: moved some arena related code into a generic arena class
* fixed typo in random bg selection, that causes no bg is created if only one bg is enabled
* fixed swapped worldstates in Ring of Valor
DB/Creature: Script a lot of creatures

By dr-j, closes #12498
Core/Battleground: fixed typo
* and fixed some warnings
DB/Misc: Fix Frogger (Naxxramas)
Closes #12434
DB/Creature: Stinker

By dr-j, closes #12502
DB/SAI: Adition to 70c82a3

By dr-j