Core/Game: Include cleanup

* Mostly aimed at removing Log/DatabaseEnv includes from other headers
* Fix most packet headers including other packet headers - moved common structures such as ItemInstance to their own files
* Moved SAI function definitions to source files (massive or requiring many different dependencies)

src/server/game/Grids/ObjectGridLoader.cpp

@@ -28,6 +28,7 @@
 #include "World.h"
 #include "CellImpl.h"
 #include "CreatureAI.h"
+#include "Log.h"
 
 void ObjectGridEvacuator::Visit(CreatureMapType &m)
 {