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/Tools/CharacterDatabaseCleaner.cpp

@@ -25,6 +25,7 @@
 #include "Database/DatabaseEnv.h"
 #include "SpellMgr.h"
 #include "SpellInfo.h"
+#include <sstream>
 
 void CharacterDatabaseCleaner::CleanDatabase()
 {